Question

In a bag, there are 2 green, 3 black, and 5 white marbles. Find the following probabilities by selecting a marble at random and THEN selecting another marble at random *without* replacing the first marble. First question: What is the probability of selecting 2 marbles at random that are both black? Second question: What is the probability of first selecting a white marble, then selecting a green marble, then finally selecting another green marble? Third question: What is the probability of selecting 5 marbles, all of them white?

Answer 1

Total number of marbles is:

• 2 + 3 + 5 = 10

First question:

• P(b and b) = 3/10*2/9 = 1/15

Second question:

• P(w, g, g) = 5/10*2/9*1/8 = 1/72

Third question:

• P(5 whites) = 5/10*4/9*3/8*2/7*1/6 = 1/252