binomial distribution

[dusky pond]

can someone please explain how u turn P(X=0) into 0.8^n

<@&791435371564892232>

I get how u do 0.05 > P(X=0)

from there onwards im lost

[plain iris]

essentially uno u can rewrite p(x>=1) as 1-p(x<=0) right?

p(x<=0) is the same as p(x=0)

so its 1-p(x=0)

and that has to be greater than 0.95

so 1-p(x=0)>0.95

now u can simplify it by subtracting one so its p(x=0)<0.05

now its a binomial distribution

so we can use the formula

nCr p^r (1-p)^n-r

nC0 =1

p^0 = 1

1-p = 0.8

0.8^n-0 is the same as

0.8^n

so

0.8^n<0.05

and then i think u know whats going on with the logs

@dusky pond

[dusky pond]

yes

[dusky pond]

ok i get it up to here

this I already knew

but using a binomial distribution is brazy

i've never seen that in my life

is this normal single edexcel maths?

[plain iris]

icl im not sure

it should be

coz i think its in the formula booklet