SOLUTION: There are 12 freshman and 9 sophomores in a class. If 5 students are selected at random, find the probability that: A) two are freshman B) at least one is a sophomore

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Question 863750: There are 12 freshman and 9 sophomores in a class. If 5 students are selected at random, find the probability that:
A) two are freshman
B) at least one is a sophomore
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

21 students: 12F, 9S

 5 students are selected at random

P(2F)  = %2812C2%29%289C3%29%2F%2821C5%29

P(at least one S) = %2821C5+-+12C5%29%2F%2821C5%29 = 1 - 12C5/21C5   (1-P(5F))