Question

There are 12 marbles in a bag, and the marbles are either yellow or green. Two marbles will be randomly picked from the bag, without replacing the first one picked. The probability that both marbles will be yellow is 5/33
. How many YELLOW marbles are in the bag?
A)
4
B)
5
C)
6
D)
7

Answer 1

If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.

Y = # of yellow marbles

Y/12 * (Y-1)/(12-1) = 5/33

Solve for Y.