ebon wadi
There are 21 students in the classroom. Among them - 2 friends (let's say A and B)). A teacher grouped students in 7 groups, 3 students in each. What is the probability that those 2 friends (A and B) will end up in the same group? Answer is 0.1.
I'm pretty sure the denominator is just 21C3 but how about the numerator?
grizzled groveBOT
slow shell
If 21C3 is your denominator, then that's the total number of possible choices for group 1. How many different group 1s include both A and B?
ebon wadi
If 21C3 is your denominator, then that's the total number of possible choices fo...
I'm not sure
P. S. I edited the question to clarify that they need to be in the same group, not in the first group.
slow shell
Ah, okay, that makes it a different question
ebon wadi
I figured this one out, however I have very similar question which I can not get the correct answer based on this question logic
give me one sec
slow shell
The quickest way to do this question is to notice that A had to be in one of the groups, and then A gets 2 partners from 20, so it's just 2/20.
ebon wadi
18 boys came to workout. 2 of them have the same name. Coach divided group of boys into 3 teams, 6 boys in each. What is the probability that boys with the same name will end up in the same team?
I'd think that this logic is correct, however the answer given in the book is 1/3. It is probable that the answer given in a book is incorrect. Can you help me clear the confusion? Am I correct?
slow shell
5/17 is right simply from the point of view that you put one of them on one team, and then the probability that the other is on the same team is 5 slots out of 17 people
I'm not quite sure why you put a 3 in the bottom denominator, but it works out. I would have put it in the numerator because there are 3 teams where that they could be on together
ebon wadi
I'm not quite sure why you put a 3 in the bottom denominator, but it works out. ...
Thank you for the answer!
.solved