Mr. Hauseman has 17 students in his class, three of whom are freshmen, and the rest are from other classes. He is going to draw two students randomly to be partners.

Question

He calculates the probability of drawing a freshman and then a junior to be
9
136
. How many juniors must be in the class?

Answer 1

3/17 are freshmen
If there are x juniors, then
P(freshman,junior) = 3/17 * x/16 = 3x/272 = 9/136
so, x=6

Answer 2

Thanks for helping me.