Probability
posted by Anna on .
A jar contains four red, four yellow, and three green jelly beans. If Joan and Jim take one jelly bean each, the probability that they both take a red jelly bean is?

prob for Joan, then Jim = (4/11)(3/10) = 12/110 = 6/55
prob for Jim, then Joan = 6/55
so prob = 6/55 + 6/55 = 12/55
or
using combinations,
prob they both pick red
= C(4,1)xC(3,1)/C(11,2) = 12/55