I have got 18 red , 12 green, 5 blue and 5 yellow balls in the bag.

Question

What is the probability that I pick excatly 2 green when I pick 4 at random ?
What is the probabily that none are yellow after I pick 4 at random ?

Thanks.

Answer 1

number of ways to get exactly two green
= C(12,2) * (28,2)

prob(exactly two green) = C(12,2)*C(28,2) / C(40,4)
= ...

prob(non-yellow) = C(35,4)/C(40,4) =