Question

Repost
Explain what you've used and why?
There are a large number of students in Luttley College. 60% of the students are boys. Students can
choose exactly one of Games, Drama or Music on Friday afternoons. It is found that 75% of the boys
choose Games, 10% of the boys choose Drama and the remainder of the boys choose Music. Of the
girls, 30% choose Games, 55% choose Drama and the remainder choose Music.
5 Drama students are chosen at random. Find the probability that at least 1 of them is a boy.

Answer 1

say s students

Boys = .6 s
.75 (.6) s = games
.1 (.6) s = drama
.15 (.6) s = music

Girls = .4 s
.3 (.4) s = games
.55(.4) s = drama
.15(.4) s = music

so number of drama students = .06 s + .22 s = .28 s
so if you pick one dram student
p one boy drama student in one pick = .06/.28 = .214
now do your Bernoulli thing for 1 of 5

Answer 2

Oh, easier find the probability that all are girls then subtract from one :)

Answer 3

How to know where to use conditional probability as in this question?

Answer 4

For all girls pretty simple
They say a large number of students so just the probability of a girl drama student to the fifth.
(.22/.28)^5 = .3
so
1 - .3 = 0.7 for one or more boys