Probability Question

Question

At a concert, there are 5 babies, 3 dogs, 7 cats, 8 adults, and 9 aliens in the audience. The headlining performer wants to get a group of 3 members from the audience on stage. What is the probability one of them is a human?

Answer 1

There are 32 members to choose from in C (32, 3) ways

There are 13 humans, and 19 non humans

So if we have exactly 1 human we can choose that human in C (13,1) ways and the other two members in C( 19.2) ways.

So the probability is [C (13,1) C(19,2)] / C (32,3) = 13 x 171 / [ 4960] = 0. 4482