#help-43

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karmic stirrup
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and what are precipitate reactions

tacit robin
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Take any inorganic salt of Ag

karmic stirrup
covert creek
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From what have learnt NaCl or any salt dissolve become Na+ and Cl-. So in solution NaCl or HCl are basically Na+, Cl-,H+ and Cl-

covert creek
karmic stirrup
tacit robin
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But yes it's true for Na

covert creek
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If for example, NaSO4 + Ba(OH)2 in solution it has Na+, SO4-, Ba2+, and OH-

karmic stirrup
#

so- this applies for soluable salts and doesn't when reacting with insoluables

karmic stirrup
upper bane
#

yes, and also applies only to acids in aqueous form ofc

tacit robin
covert creek
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you see Ba2+ and SO4- make BaSO4 which doesn't dissolve in water and that's why NaSO4 and Ba(OH)2 has reaction

karmic stirrup
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okay! I got what i wanted... Fionna, ping me when you're done and ill close the channel.

covert creek
#

that's what I think

plush lichen
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what chem yall in

covert creek
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why it form as solution lol, because like in NaSO4 + Ba(OH)2

karmic stirrup
plush lichen
#

ap chem?

covert creek
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Na+ and (OH)- basically have no react it just floating in the solution

covert creek
karmic stirrup
#

you dont have helper role

covert creek
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Not this me

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other me

karmic stirrup
#

sure.

karmic stirrup
covert creek
#

Na2SO4 -> Na+ and SO4(-2)

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BaCL2 -> Ba2+ and Cl-

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these ions just bond and unboud with each other in the solution as if it get dissolved in water

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But the thing is

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Ba2+ and SO4(2-) form BaSO4 which can be dissolved

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can't

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So all the Ba and SO4 form BaSO4 and sink to the bottom

covert creek
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so ig the same thing happens with the reaction you asked

karmic stirrup
#

I dont fully get it but- yeah i do understand what you're trying to say

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but rn i have to go back to electricity

karmic stirrup
#

bye fie!

covert creek
#

cya

karmic stirrup
#

.close

compact pewterBOT
#
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zenith barn
#

how do you get alpha in the formula to the right,, im starting to forget all of my trigonometry worksheets

grizzled geyser
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Letting $r = \sqrt{a^2+b^2}$, you know that $r \sin (\theta + \alpha) = r \sin \theta \cos \alpha + r \cos \theta \sin \alpha$

boreal girderBOT
grizzled geyser
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You then have to solve for $a = r \cos \alpha$ and $b = r \sin \alpha$

boreal girderBOT
zenith barn
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ah,, so cosalpha = sinalpha where x = pi/4,,, i think

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i found the sheet i was looking for let me relearn

grizzled geyser
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You mean alpha = pi / 4, but close enough

zenith barn
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i miss when i understood this

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ah, take the radius then divide it from sinx + cosx to extract r from both of them

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managed to solve it 🎉

worldly snow
zenith barn
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ouh wdym?

worldly snow
zenith barn
#

thats true..the way our tutor worksheets did it is like seperate them into simpler pieces and explore those fundamentals before teaching you how to integrate them together

bleak dock
boreal girderBOT
zenith barn
zenith barn
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hm,, if a function f(x) repeats at a period a and is integrated as F(x) from ma to na where m and n are integers, the result of F(c+k) equals F(c) ,i assume

compact pewterBOT
#

@zenith barn Has your question been resolved?

compact pewterBOT
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floral kelp
#

guys does anyone understand this notes?

compact pewterBOT
floral kelp
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why is there 2 different formulas for standard deviation?

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the “s” and σ

upper bane
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you mean why the population and sample SD have different formulas?

floral kelp
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yes

upper bane
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a sample is a subset (or a portion) of the whole population. the difference in formulas accounts for the fact that by choosing an arbitrary sample, we may have biased the sample

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the -1 attempts to correct for this bias

floral kelp
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ohhhhh

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so “sample” is “biased”?

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like we consider it as a biased estimate?

upper bane
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not all samples are biased, but by picking a sample, we consider it to be biased, yes

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you may be interested in studying Bessel's correction, which is exactly this.

floral kelp
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if the question states “20 randomly chosen”

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does this mean it is unbiased since it is random?

upper bane
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normally if the question says "sample" or "chosen", then use the sample formulas

upper bane
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randomness is not the same as fairness

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something that is random is not necessarily fair or uniform

floral kelp
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oooooo

upper bane
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just ask any gacha player

floral kelp
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so we can only use the population formula if it is “fair”?

upper bane
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well, the population represents the whole picture

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there's no contest about fair or unfair because you have the whole picture. if the population is biased towards one side, then it's the nature of that population

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you can't say a population is biased, because there's nothing to compare against

floral kelp
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ohhhh i get it

upper bane
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if you have something bigger to compare against, then your population is really just a larger sample.

floral kelp
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i have another questionn

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for confidence interval of normal distribution, why do we use sigma in the formula?

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is it bcs normal distribution is not biased?

upper bane
floral kelp
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but aren't we supposed to use s for sample?

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not sigma

upper bane
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oh, but look carefully

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the variance is coming from the population

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only the mean is from the sample

floral kelp
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ohhh

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what about confidence interval for large samples

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wait lemme take pic of the box

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oh wait this is actually obvious already

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it uses s because it is a sample rightt?

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i think i get itt already

floral kelp
upper bane
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nps

floral kelp
#

.close

compact pewterBOT
#
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compact pewterBOT
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ornate sable
#

I simplified sinx and x. I feel like it could be clear to say that sin x < x based on this but also I feel like it could be too big of an assumption but I don't know how I would actually go about it

short lantern
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what is the area of the sector?

ornate sable
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idk all we have defined is the area of a circle of radius 1

short lantern
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you also have the angle is x

ornate sable
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yes?

short lantern
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do you know the formula for area of a sector given radius and angle?

ornate sable
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well I guess xr^2

short lantern
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close

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the area of a circle is pi*r^2

ornate sable
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how? isn't it just swiching variables in our first equation?

short lantern
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the angle is x/(2pi) of a full circle

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so you want x/(2pi) of the area

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i.e. (x/(2pi))*(pi*r^2)

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which is (x*r^2)/2

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what is the area of the triangle OPA?

ornate sable
ornate sable
short lantern
short lantern
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A goes*

ornate sable
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oh wait but that isn't a triangle

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oh outside teh circle

short lantern
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yes, a sector is a part of a circle, like a pizza slice

ornate sable
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1/2 sinx

short lantern
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what does that signify

ornate sable
#

half the height

short lantern
#

what exactly are you looking for

ornate sable
#

the relation between x and sinx

short lantern
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and how can we show this relationship?

ornate sable
#

ok so what I think what your saying is that x represents the circular sector that we are looking at in our case and 1/2sinx is the area of the triangle which is already bigger than that circular sector and then if we multiply by 2 to obtain sin x it will most definitely be bigger

short lantern
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draw the triangle

ornate sable
short lantern
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are those three points O, P, and A

ornate sable
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yes

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oh wait no

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not p

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wait I ddint' draw this right

ornate sable
short lantern
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the entire point of this hinges on knowing exactly what you are looking at

ornate sable
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ok but the triangle outside of the circle could not have p as a point

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oh wait

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I think I see

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nvm

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regarding what you said early are you saying that I set up the image incorrectly?

short lantern
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yes

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the triangle is not correct

ornate sable
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ok

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ok so we want to find the area of opa but if oa is cosx and pa is sinx how can it not be 1/2sinxcosx?

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wait that is opa not OPA

short lantern
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the triangle does not have to be a right triangle

ornate sable
short lantern
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yes

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that is your triangle

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what is the area of this triangle

ornate sable
#

ok so for the base I will make a smaller triangle and then (1-cosx)^2 +sin^2x = b^2 and then I can find the height by h = 1 - (b/2)^2 so area is 1/2 [sqrt (1-cosx)^2 +sin^2x ] * [(1- sqrt (1-cosx)^2 +sin^2x/2)^2 ]

short lantern
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theres a much easier method

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what is the base at the bottom of this triangle?

ornate sable
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the one from purple and blue?

short lantern
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OA

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what is OA

ornate sable
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oh I misread it as triangle sorry OA is 1

short lantern
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what is the height from P to OA

ornate sable
#

sinx

short lantern
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ok so what is the area of the triangle OAP

ornate sable
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I don't see how it can be sinx

short lantern
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its not

ornate sable
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ok I thought that was going to be the natural concllusion becsause 1 and sinx

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but still that doens't tell us about the base or the height the only things they do is let us calculalte it which is what I did above

short lantern
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use the formula for area of a triangle

ornate sable
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wait your looking at the triangle differenlty I see now

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but then teh area is sinx the base we found is 1 and the height is sinx

short lantern
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what is the formula for area of a triangle

ornate sable
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oh 1/2sinx

short lantern
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thank you

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now real quick before we continue, which area is bigger, the sector or the triangle?

ornate sable
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the sector

short lantern
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ok good

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moving on

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i said earlier the area of a sector is (x*r^2)/2, would you like me to show you how we got that again?

ornate sable
#

no I see it

short lantern
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ok, what is the radius of our circle

ornate sable
#

1

short lantern
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ok plug that in for r

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what do you get for the area of the sector

ornate sable
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yes x/2

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mutlilpllying both by 2 then?

short lantern
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ok, now we know the sector is bigger, so what will an inequality look like

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yes

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then you multiply bu 2

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and it shows what you wanated

ornate sable
#

yes and then I am assuming what I sent the first time does not because it is not explicitly easy to see

short lantern
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it also operates on a wrong assumption of what triangle OAP is

ornate sable
#

wait im referring to this one

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I don't use triangles here

short lantern
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imma be completely honest i have no idea what youre doing here

ornate sable
#

all this was was plugging in for r in then isolating for sinx

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also for the second part could you not just say apply the same method because anything in an absolute value is positive so wouldn't it just be doing the same thing but rewritten with |sinx| and |x|

compact pewterBOT
#

@ornate sable Has your question been resolved?

compact pewterBOT
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wet vine
compact pewterBOT
kind viper
#

,rccw

boreal girderBOT
wet vine
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How do you do a problem like this? And if i get a problem similar to it in the future how would i do it myself

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/ how would i identify it

kind viper
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find the areas of the white triangles (AXY, YDC, CXB)

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you can find them as fractions of the rectangle

wet vine
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Ye ik

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But idk how

kind viper
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do you know how to find the area of a right triangle in general

wet vine
wet vine
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Oh wait

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They're mid points

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Hol up

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Lemme try smthing rq

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Wait nvm i got the anwser

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😭

bleak dock
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oh lmao this is PSLE

wet vine
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I over complicated it for myself

wet vine
bleak dock
#

it's not PSLE? damn

wet vine
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Whats psle?

bleak dock
#

yeah no you're across the border in Malaysia I guess

bleak dock
wet vine
#

💀 nah lmao

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Aint this hard in year 6

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Eh

bleak dock
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some of the challenge problems on the PSLE are, anyways

wet vine
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Idk im js dumb

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Anyways imma go

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Cus i found the anwser

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🔥

#

.close

compact pewterBOT
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wet vine
#

Uhhhh how to do this

compact pewterBOT
bleak dock
boreal girderBOT
bleak dock
covert grove
#

اه

#

hi

compact pewterBOT
#

@wet vine Has your question been resolved?

compact pewterBOT
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wet vine
compact pewterBOT
wet vine
#

But anwser is 6

cursive harbor
bleak dock
#

hopefully you're on the same page as me, where you have 2 J pieces= 4 cm x 3 cm rectangle

wet vine
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Since it wants a 10 x 15

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I made a

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12 x 9 square

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Then left with one side which is 3 x 15

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And one side which is 1 x 12

bleak dock
wet vine
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No like 9 x 12

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Its under 10 x 15

bleak dock
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ohhhh okay, then yeah, keep going

wet vine
#

Then for the 3 x 15 i could only fit like

bleak dock
#

,calc 10 * 15 - 9 * 12

boreal girderBOT
#

Result:

42
bleak dock
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okay hmm

wet vine
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Like 5 of em

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Which leaves 3 empty space each time

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Making it 15

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Then add the 1 x 12

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Cus u cant rly put the j there

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So 27

bleak dock
#

yeah the packing is not obvious then

wet vine
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Ye

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Is it that we have to surround the 10 x 15 square with the 3 x 4 square first so theres more space in the middle?

bleak dock
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oh yeah, so notice how I rotated the 3 by 4 rectangle the other way, in the bottom right corner

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you can fill the empty space at the top with the 4 by 3 rectangles

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yes I also get 6 this way

wet vine
#

Ohhhh

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I understand it now

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Ty

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.close

compact pewterBOT
#
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compact pewterBOT
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wet vine
compact pewterBOT
wet vine
#

Wouldn't the awnser to this be 52?

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My anwser sheet says 51

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But 51 only makes it so theres one of each ball colour left

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It has to be 52 so all colours of 1 sack will be picked

junior mantle
junior mantle
covert creek
#

,rccw

boreal girderBOT
junior mantle
compact pewterBOT
wet vine
#

7 , 8 ,9 ,10 ,11 , 12

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Each represent a bag

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With the respective number of balls

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Worst case scenario

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U pick every single colour expect for one

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Make its so u now picked 6 + 7 + 8 + 9 + 10 + 11 balls

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So 51

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So now each bag has only 1 ball left

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So u need to pick 1 more ball so u have a complete set

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So its 51 + 1

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= 52

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But my awnser sheet says 51

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Am i missing something

junior mantle
#

Why 6+

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There is no group of 6 balls?

compact pewterBOT
#

@wet vine Has your question been resolved?

compact pewterBOT
#
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low pulsar
#

im so confused with this

compact pewterBOT
low pulsar
#

if you need me to translate english i can

noble sorrel
#

yes

low pulsar
# noble sorrel yes

Pure water is added to 50 mL of a 30% acid solution. The rule C(x)= (15)/(x+50)
​ represente the acid concentration as a function of the quantity
x of water added to the solution. All quantities are in milliliters.

a) In the Cartesian plane opposite, draw the graph of this function for values of
x
x up to 150 mL.

b) What is the y-intercept of this function?

c) How much water must be added for the concentration to be less than 1%?

d) What rule allows calculating the concentration of 80 mL of a 40% acid solution if
x milliliters of water are added?

toxic cipher
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Choose an appropriate scale for the horizontal and vertical axes, and plot the points

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then draw a straight line through those points

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also label the axes

low pulsar
#

is there a reason or nahh

toxic cipher
low pulsar
#

aleight

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so can i pick like x = 130

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and find C(x)

toxic cipher
#

yes

low pulsar
#

kk

toxic cipher
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x = 150 has to be one of the values in the table though

low pulsar
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alright also

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when i do 130

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it gives a really small number of y

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1/12

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bit hard to place that on the graph

toxic cipher
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hmm

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notice that we're dealing with percentage concentration here

low pulsar
#

yeahj

toxic cipher
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At x = 0, C(x) = 0.3

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the question states that x = 0, the percentage concentration is 30%

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so you can convert everything to percentage

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(at least i think)

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but you will need to label your vertical axis appropriately

low pulsar
#

so i convert the ml into percentage?

toxic cipher
#

nono like you convert your 1/12 into percentage

low pulsar
#

its 8.33^

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8.33%

toxic cipher
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yup

low pulsar
#

what do i do with that

toxic cipher
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i would just choose something like x = 0, x = 50, x = 100, and x = 150

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cause those give nice numbers

toxic cipher
low pulsar
#

like x = 130

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y = 8.33

toxic cipher
low pulsar
#

i got it like this

toxic cipher
#

,tex \begin{table}[]
\begin{tabular}{l|l|l|l|l}
x & 0 & 50 & 100 & 150 \ \hline
C(x) & ? & ? & ? & ?
\end{tabular}
\end{table}

boreal girderBOT
low pulsar
#

oh ok

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so x 130 and 8,33

low pulsar
#

right?

toxic cipher
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the '?' is a placeholder

low pulsar
#

ah alright

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30%

toxic cipher
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and then?

low pulsar
#

then i have 130

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which is 8.33%

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now ill calculate 150

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which is the max

toxic cipher
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why did you choose 130 btw lol

low pulsar
toxic cipher
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it'll give such a weird value of C(x)

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next time you should choose something that'll be easier to calculate and wont require rounding

low pulsar
#

alright my fault there

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when its 150

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its 7.5%

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thats 3 values right

toxic cipher
#

okay

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yup

low pulsar
#

alright

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in the graph

toxic cipher
#

now look at your grid

low pulsar
#

in the y axe

toxic cipher
low pulsar
#

is it like %

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like 5%

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then 10%

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15%

toxic cipher
#

lemme check

low pulsar
#

in the y axe i probably gotta jump by 20

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so like 0 20 40 60 80 100

toxic cipher
#

no an increase of 5% per square would be too small

low pulsar
#

10%

toxic cipher
#

look at the range of values you got for C(x)

low pulsar
#

i got

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30 8.33 and 7.5

toxic cipher
#

you have at x = 0, C(x) = 30% and at x = 150, C(x) = 7.5

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so the maximum will be when x = 0

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and the range for C(x) is 30 - 7.5 = 22.5%

low pulsar
#

wait il lshow u osmething

toxic cipher
#

so ideally you would want 30% to be near the top of the graph

low pulsar
#

i meant this

low pulsar
toxic cipher
#

yea ik

low pulsar
#

to make it accurate?

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we should do 2.5 then

toxic cipher
#

that's what i was thinking

low pulsar
#

yeah

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also w cant do 10

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because it doesnt reach 105

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150

toxic cipher
#

yup

low pulsar
#

so we should do 15?

toxic cipher
#

i think 15 would work

low pulsar
#

alright

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yeah it does

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did my line

toxic cipher
#

can i see it?

low pulsar
#

looks like this

low pulsar
toxic cipher
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uh no that shouldnt be how it looks

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can you mark out the vertical and horizontal axes first?

low pulsar
#

a;rogjt

toxic cipher
#

and then plot out the points

low pulsar
#

wait

#

its a rational function

#

has to look like this

toxic cipher
#

hm

#

i think you need to record more values of x and C(x) in your table

low pulsar
#

alright

toxic cipher
#

like x = 50 and x = 100

low pulsar
#

i did 75 is that ok?

toxic cipher
#

btw i was wrong in saying you only needed 3 values just now, sorry

low pulsar
#

no worries dude

toxic cipher
low pulsar
#

y is 12

#

when its 75

toxic cipher
#

yh

low pulsar
#

now it looks ike this

#

wait forgot one

toxic cipher
#

right

#

so you should be able to draw a line through that

#

it'll be a curve

low pulsar
#

yes

#

drew

toxic cipher
#

you want to do all the markings for your horizontal and vertical axes

#

for your vertical axis you stopped at 20 for some reason

low pulsar
#

i didnt

#

its just for that screenshot idid

#

but on my paper i wrote it all

toxic cipher
#

oh ok

#

anyways the last step (which should have been the first step) is to label the axes

low pulsar
#

whats label

#

wdym

toxic cipher
#

like

#

your vertical axis will be "percentage concentration"

#

you can write that at the side of the grid

#

and then your horizontal axis will be "x"

low pulsar
#

oh alr

toxic cipher
#

you can write that at the bottom of the grid

low pulsar
#

got u

#

thanks for ur help

toxic cipher
#

and that should be part a'

low pulsar
#

yeah

#

part b is 30

#

right

toxic cipher
#

30%

#

the percentage sign is important

low pulsar
#

ah

toxic cipher
#

part c is reading off the graph when y = 1%

low pulsar
#

we have to do

#

1% divided by 100

#

then replace C(x) by 0.01

toxic cipher
#

oh yeah you can do that too

#

they didnt say "using the graph"

#

actually your method is better

low pulsar
#

yeah

#

0.01 = (15)/(x+50)

toxic cipher
#

wait a sec

low pulsar
#

do we do (x+50) both sides

toxic cipher
#

@low pulsar sorry i was doing smth just now

low pulsar
#

dw

#

i found it tho

#

i did (x+50) both sides

toxic cipher
#

so this is actually a very common mistake that students make

toxic cipher
#

the question states "how much water must be added for the concentration to be less than 1%"

#

so you want to make an inequality not an equality

low pulsar
#

but how do we know its inequality

#

what if it said to be 1%

#

then its >= ?

#

or =

toxic cipher
#

huh

#

if it said to be 1% then it would be an equality

low pulsar
#

oh

toxic cipher
#

it says less than 1% so it's an inequality

low pulsar
#

alr

#

what if it said more

toxic cipher
#

well then you would do >

#

it's less than so it's '<'

low pulsar
#

alright i see

toxic cipher
#

yeah

#

i made this mistake like some time ago

#

so i remember it ;(

low pulsar
#

😭

#

damn

#

i've obtained 0.01 < (15)/(x+50)

toxic cipher
#

nono it's $C(x) < 0.01$

boreal girderBOT
toxic cipher
#

meaning $\frac{15}{x + 50} < 0.01$

boreal girderBOT
low pulsar
#

oh wait yeah we want to know how much will be less than 0.01

#

mb

#

usually what i do here

#

wait i dont think we can do what i was gonna do

#

but i can tell u

toxic cipher
#

ok

low pulsar
#

so what i was gonna say

#

we do -0.01 both sides

#

to put it 0

#

then we put the -0.01 on the same denomiantor

#

as x+50

toxic cipher
#

uhh

low pulsar
#

then we do

#

the curve method

#

like this

#

might be wrong tho

toxic cipher
#

that seems overly complicated

#

you can multiply (x + 50) to both sides

low pulsar
#

alright

#

sorry

#

@toxic cipher back

#

aslright

toxic cipher
#

aight

low pulsar
#

0.01x + 0.5 > 15

toxic cipher
#

okay

low pulsar
#

now

#

0.5 bothj sides

#

wait

#

we cant

#

its not an equality

#

?

toxic cipher
#

wdym

low pulsar
#

we can do -.05?

toxic cipher
#

yes

low pulsar
#

ah alr

#

1450 = x

toxic cipher
#

we're not doing an equality

#

we're doing an inequality

low pulsar
#

mb

#

x > 1450

toxic cipher
#

yup

low pulsar
#

so x has to be

#

1451

#

for it to be below 1%

toxic cipher
#

nono x doesnt have to be an integer

low pulsar
#

what do i write for c then

#

only x > 1450

toxic cipher
#

You can just write a statement saying "For the percentage concentration of water to be less than 1%, the amount of water added must be greater than 1450 ml"

low pulsar
#

alright i see

toxic cipher
#

honestly part c is written badly cause there isnt any one answer that satisfies it

#

but a range of answers

low pulsar
#

yeah exactlyt

#

for d)

#

pretty sure its

#

0.4 = (15)/(80+50)

#

nvm im wrong

#

its only asking for the equation

toxic cipher
#

idk about that

we have 80 ml of a 40% acid solution so we cant use back C(x)

low pulsar
#

80 ml of a 40% solution

toxic cipher
#

first you want to calculate the amount of acid in ml initially

low pulsar
#

so y is 0.4 and x is 80

toxic cipher
#

nono i think they're asking for an equation which describes the concentration of the solution as a function of x

low pulsar
#

1 ml how much % acid solution

#

hm

#

wait we cant use the rational equation like last time?

#

C(x) = (?)/(x+?)

#

?

toxic cipher
#

wdym

#

like we want a new function to describe the concentration given the amount of water added

#

we cant use back the previous one because the initial parameters are different

low pulsar
#

can we use that format

toxic cipher
low pulsar
#

alright

#

its gonna be

#

im actually not sur

toxic cipher
#

well

#

i think it would be nice if you understood what C(x) actually means and how it derived

#

So in the original scenario, we have 30% concentration of a 50 ml acid solution initially

#

what would be the volume of acid present initially?

toxic cipher
toxic cipher
#

do you know how to calculate concentration?

low pulsar
#

like in ml then we put into %?

toxic cipher
#

like in general

#

okay so concentration of acid in a solution is $\frac{\text{volume of acid}}{\text{total volume of solution}}$

boreal girderBOT
low pulsar
#

ah

#

initially it was 15 no?

toxic cipher
#

yes

low pulsar
#

alright

#

so this time

#

we dont know

#

this is what i wrote for now

#

80/? = ?/0.4

toxic cipher
#

okay wait

#

what is the volume of acid initially? will it change?
what is the total volume of the solution initially? will it change?

low pulsar
#

15 it wont change

#

yes it can change because its x+50

#

we can change x

toxic cipher
#

right

#

so what would be the concentration?

low pulsar
#

the %

toxic cipher
low pulsar
#

we gotta know x

#

for that

toxic cipher
#

i mean like

#

you know the total volume and you know the volume of acid

#

the concentration would be $\frac{\text{volume of acid}}{\text{total volume}} = \frac{15}{x + 50}$

boreal girderBOT
toxic cipher
#

do you understand?

low pulsar
#

x+80 is total volume

low pulsar
toxic cipher
#

and the initial volume of acid for the second case?

low pulsar
#

it doesnt give that information

toxic cipher
#

yes it does

#

you know the total volume initially, and you know the concentration initially

low pulsar
#

but i only have 80 ml solution acide

#

at 40%

toxic cipher
low pulsar
#

oh

#

its 32

toxic cipher
#

yeah

low pulsar
#

i see

#

c(x) = 32/x+80

toxic cipher
#

yes

#

that's it

low pulsar
#

oo

#

alright i see

#

well ty for ur help dude

toxic cipher
#

no problem

low pulsar
#

.close

#

.close

compact pewterBOT
#
Channel closed

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compact pewterBOT
#
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compact pewterBOT
#
Channel closed

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#
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compact pewterBOT
cursive harbor
#

.close

compact pewterBOT
#
Channel closed

Closed by @cursive harbor

Use .reopen if this was a mistake.

cursive harbor
#

.reopen

mild sky
#

Xavier the tester

cursive harbor
#

Why did it work last time

native shard
verbal kiln
cursive harbor
#

What

viscid canopy
#

!xy

compact pewterBOT
#

Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.

mild sky
#

!nogpt

compact pewterBOT
#

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

native shard
#

!status

compact pewterBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
mild sky
cursive harbor
#

Lmfao

strange pendant
#

!done

compact pewterBOT
#

If you are done with this channel, please mark your problem as solved by typing .close

cursive harbor
#

.reopen

#

Why did it work last fime

mild sky
#

.reopen

cursive harbor
#

Am I hallucinating

verbal kiln
#

People bombarding this poor guy

viscid canopy
#

what are u talking about

cursive harbor
strange pendant
#

its already open

cursive harbor
#

.close

verbal kiln
cursive harbor
#

No it's not

viscid canopy
#

.close

weak cobalt
#

It's clopen

mild sky
#

.close

verbal kiln
#

Is the bot borken?

strange pendant
#

seems broken to me

verbal kiln
unique lynx
#

It's some kind of broken -- it's spamming lots of error messages to its internal log channel.

cursive harbor
#

Ah interesting

verbal kiln
#

Xavier do you have any comment on this?

cursive harbor
#

Are the errors related to what I'm doing or is the bot just buggy rn

cursive harbor
#

They're an admin lmao

verbal kiln
mild sky
#

If the logs are not in 5 different colors I am going to be sad

strange pendant
#

would be useful if the users with the bot enthusiast role have access to the logs

unique lynx
#

Access to the log channel comes with being a seniormod on indefinite break.

strange pendant
#

so they can fix this mess

cursive harbor
#

Would reveal too much sensitive info

verbal kiln
mild sky
verbal kiln
paper anchor
#

Well this help channel looks fun

digital lark
#

Hello

verbal kiln
paper anchor
cursive harbor
#

.close

strange pendant
verbal kiln
cursive harbor
#

.reopen

paper anchor
#

OMG it's still not working

cursive harbor
verbal kiln
#

!bnuuy?

compact pewterBOT
verbal kiln
#

Oops

paper anchor
#

never knew that

cursive harbor
#

It seems to be working in other places

paper anchor
#

Maybe wait 15 minutes

verbal kiln
cursive harbor
#

Yes

#

I thought I found a vulnerability and I did

paper anchor
#

It'd ask whether your question has been answered and you could just tick it

cursive harbor
#

The channel is closed lol

paper anchor
#

Oh whoops

cursive harbor
#

It worked when I tried to close it

#

And then died when I tried to open it back after deleting my original message

paper anchor
#

Ahhh I see, but it's not reopening right

cursive harbor
#

Yeah

#

It should become available or hidden soon enough ig

compact pewterBOT
#
Available help channel!

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pale ocean
#

Not really math, but how should I think abt this?

signal goblet
compact pewterBOT
#

@pale ocean Has your question been resolved?

#
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flint wing
#

i dont understand why the last three rows are true?

old mica
#

since p ^ (p -> q) is false, the entire implication (p ^ (p -> q)) -> q is true

flint wing
old mica
#

if you have an implication P => Q, then it's true when P is false

#

that's all the sentence is saying

flint wing
#

ohh ok can you give an example like in words for me please

old mica
#

I like to think about vacuous truths in terms of lying

rigid perch
#

"if it rains tomorrow then i'll take the bus"
if it's sunny tomorrow i might walk or take the bus, but either way I didn't lie to you, my statement was true

old mica
#

let's raise the stakes catthimc

#

let's say P is "if I quit mathcord tomorrow", and Q is "then I will die"

#

when am I lying to you?

#

if I quit mathcord tomorrow and I die, I told the truth and you couldn't call me a liar (implication is true)

#

if I quit mathcord tomorrow but I surivive, then I lied to your face and you can call me a liar (implication is false)

#

now if I don't quit mathcord tomorrow and die, then you can't call me a liar still

#

for all you know, I was gonna die either way

#

so the implication is true

#

likewise, if I don't quit mathcord tomorrow and I still survive, you also cannot call me a liar

#

so P is false means the entire implication is true happy

#

note to any onlookers: I will not be quitting mathcord tomorrow, and I will probably not die tomorrow either catthimc

flint wing
old mica
#

I didn't tell you what might happen if I didn't leave the mathcord catthink

#

so you can't call me a liar catuwu

#

and as it happens, my life force is bound to this server kannafire

flint wing
#

thank u both

old mica
flint wing
#

.solved

compact pewterBOT
#
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compact pewterBOT
#
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rotund moth
#

i need help with this question

compact pewterBOT
rotund moth
#

i understand the formula

#

but idk where to start

#

i thought i had to find the roots but

#

'its about the y-axis

#

so im not sure

glass oracle
#

okay, have you done solids of revolution around the y axis before?

rotund moth
#

ye

#

do i need to write the equation in terms of y?

glass oracle
#

ah right, can you rewrite the equation as a function of y

#

yeah

rotund moth
#

ok

glass oracle
#

you also need to find bounds in terms of y

#

so that's probably 0 and the y coordinate of the maxima

rotund moth
#

oh like

#

oh yeyeok

glass oracle
#

the integration bounds yea

#

oh wait i might be dumb sorry

#

this is probably gonna find the volume left of the curve

rotund moth
#

heh?

#

i have the solution but i js dont know where everythihng came from

glass oracle
#

like this part

rotund moth
#

rught

#

right

glass oracle
#

i haven't done solids in a while, i think you need volume by shells for this (?)

#

one sec lemme check my notes

rotund moth
#

thats what they did

#

where did 81 come from....

glass oracle
#

oh wait that's still volume by washers

glass oracle
# glass oracle like this part

okay so they're using the original method, calculating the full volume from the y axis then subtracting the volume i highlighted here

#

81 is the y coordinate of the maxima when a=18

#

so your integrating between 0 and 18 along the y axis

#

you find the volume by rotating the blue region around the y axis then subtracting the volume of the red region rotated around the y axis

compact pewterBOT
#

@rotund moth Has your question been resolved?

rotund moth
glass oracle
#

yup

rotund moth
#

but 81?

glass oracle
#

so the maxima is halfway between the roots x=0 and x=18

rotund moth
#

omg right

#

ok

#

so when x=9?

glass oracle
#

yaya

rotund moth
#

ohhhh

#

omg

#

thank you

#

SJSJS I LITERALLY HAVE A TEST LIKE

#

IN LIKE 30 MINS

glass oracle
#

np! sorry for being confusing before haha

rotund moth
#

RAH IM COOKED

rotund moth
glass oracle
#

rahhh lock in you got this

rotund moth
#

at least i got it in the end

rotund moth
compact pewterBOT
#
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#
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quartz sorrel
#

Nontrivial combinatorics
How many of these are there as the number of let's say legs grows (symmetry reduced and not)
The leg connectors can only be at either edge, the spike on each of the connectors has to exist either inside or outside aka both variables are xor
n*90deg rotation, 4 lines of symmetry of the square or a combination of the two are counted

quartz sorrel
#

Without the spike swappability it should be

boreal girderBOT
#

tomka700

quartz sorrel
#

And

boreal girderBOT
#

tomka700

quartz sorrel
#

Respectively

#

It can be mapped to a 2x(2n-1) or (2n-1)x2 matrix where there is exactly one nonzero (1 or 2 depending on spike) in every even row/col eg
00
10
00
02
00

#

<@&286206848099549185>

compact pewterBOT
#

@quartz sorrel Has your question been resolved?

quartz sorrel
#

I don't know whether or not there is a closed formula as this is a result of a pet project but it doesn't feel that complicated

compact pewterBOT
#

@quartz sorrel Has your question been resolved?

boreal girderBOT
#

tomka700

compact pewterBOT
#

@quartz sorrel Has your question been resolved?

worldly snow
#

help

#

The Philippine eagle is one of the largest and rarest birds in the world. Its powerful wings spread to about 2.4 m. What is the measurement of its wingspan in feet?
A metric ton, abbreviated as “t”, is a unit of measurement used for large masses such as those of cars, planes or heavy construction equipment. The weight of a compact excavator is 1.893 t. If 1 t = 1000 kg, what is the weight of the compact excavator in kilograms?
A kilogram of carrots costs 60 pesos. How much does 750 g of carrots cost?
!help

compact pewterBOT
compact pewterBOT
#

@quartz sorrel Has your question been resolved?

compact pewterBOT
#
Channel closed

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floral kelp
#

guys for this question, i noticced that they use CLT in 12a. why do they use CLT if the distribution is already normal?

floral kelp
#

i was thinking that this is probably because it will be asked in the following subquestion but the first time i did it, i did not apply CLT at all, so the answer is wrong

upper bane
#

that's the z-score calculation, not a CLT application

floral kelp
upper bane
#

that's a z-test

floral kelp
#

whats that

upper bane
#

hm, I might not be the best person to explain the diff between z-score and z-test

floral kelp
#

hmmm

#

but if questions like that appear, am i just supposed to apply CLT

#

i would not know they would apply CLT if i didnt see the mark scheme

upper bane
#

I wouldn't call this an application of a CLT, but I also am not sure how to start explaining z-tests, so

floral kelp
#

oooooo

#

okok

upper bane
#

i did nothing this time

floral kelp
#

btw for letter c

floral kelp
#

does anyone know how CLT is used 😂

#

why does it says CLT is necessary but at the same time i cant spot any working that applies CLT

compact pewterBOT
#

@floral kelp Has your question been resolved?

compact pewterBOT
#

@floral kelp Has your question been resolved?

limber plover
odd pewter
#

,help

boreal girderBOT
#

A brief description and guide on how to use me was sent to your DMs!
Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!

floral kelp
#

Like is it invisible

limber plover
#

@floral kelp It turns out my statement was little imprecise. Here's what GPT says and answer your questions also:

floral kelp
#

yess i think i get it

#

it’s approximated and not changed

floral kelp
# floral kelp btw for letter c

but i don’t understand in letter c, they said it’s necessary to use CLT for part b. But in part B, they did not use CLT at all

upper bane
#

!noai

compact pewterBOT
#

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

limber plover
upper bane
#

nps

limber plover
limber plover
floral kelp
#

will close the channel

#

.close

compact pewterBOT
#
Channel closed

Closed by @floral kelp

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#
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fallow coral
#

Can somebody explain how Σ(sin^2B-sin^2C) is expanded here?

grim adder
grim adder
fallow coral
#

shouldn't there be lower limit and upper limit ? How do I expand?

fallow coral
grim adder
fallow coral
grim adder
#

so like aSin(B-C) + bSin(C-A) + cSin(A-B)

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thats what you have to prove to 0

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since theres no real way to express this in a general summation without getting it too clustered they just leave it out

grim adder
fringe granite
#

Omaxe

grim adder
#

what now

fallow coral
grim adder
fallow coral
#

thanks

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.close

compact pewterBOT
#
Channel closed

Closed by @fallow coral

Use .reopen if this was a mistake.

grim adder
#

wlcm

compact pewterBOT
#
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Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
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polar laurel
#

HELP

compact pewterBOT
polar laurel
#

I need someone to check my work

#

and answers

#

i think i did it correct

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but i wanted to backcheck with a professional

verbal kiln
# polar laurel HELP

Just for future reference, can you please post the image/question as your first message so the bot doesn’t pin greetings or requests for help? This way, if the conversation continues for long, helpers don’t have to dig backwards to find the problem you are having trouble with. catlove

grim adder
# polar laurel

just put the value's you found back into the original equation

#

if the result is 0

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then it's correct

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if welp, try again

verbal kiln
compact pewterBOT
#

@polar laurel Has your question been resolved?

#
Channel closed

Closed by @polar laurel

Use .reopen if this was a mistake.

#
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Remember:
Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
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clever stratus
#

how many of the first 10,000 positive integers contain the digit-pair 43 in that order

clever stratus
#

i got like

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xx43 as 100
x43x as another 100
43xx as another 100

but answer says its 299

clever stratus
#

that js counts as 1

tired bear
#

in two cases

clever stratus
#

oh

noble sorrel
#

u can't put 0 in front

grim adder
#

ohh nvm it can be multi digits

clever stratus
grim adder
#

dont mind me heh