Question

A bag contains 5 blue marbles, 6 red marbles, and 9 green marbles. Two marbles are drawn at random, one at a time. What is the probability of selecting a green marble and then, without replacing it, a red marble? A. 9/38 B. 9/190 C. 27/190 D. 3/38

Answer 1

Your answer would be C. 27/190.

This is because the probability of choosing green as the first marble would be 9/20, as there are 20 marbles in total and 9 of those are green.

The probability of choosing a red marble as the second marble would be 6/19, as no red marbles would have been lost if green was picked first, but there would be one less marble in total.

The 'and' rule for probability, the one that is used to determine the probability of P(A) and P(B), is to multiply, so we need to do 9/20 × 6/19 = 54/380 = 27/190.

I hope this helps!