Find Probability

Question

Find the probability for the experiment of drawing two marbles at random (without replacement) from a bag containing three green, four yellow, and three red marbles.

Both marbles are red.

Answer 1

First pick: 10 marbles in bag. 3 red marbles. Probability of picking red marble is 3/10

Second pick: 9 marbles in bag, 2 red marbles. Probability of picking red marble is 2/9

Probability 1st and 2nd pick is red marble: 3/10 * 2/9 = 6/90 = 1/15