21. A bag contains 10 solid-colored marbles of the same size: 3 red, 2 green, yellow, and 4 blue. Which of the following expressions gives the probability of drawing, at random and without replacement, a blue marble on the 1st draw, a green marble on the 2nd draw, and a blue marble on the 3rd draw?

Answer and Explanation

Your Answer is

Correct Answer is D

Explanation

There are a total of 10 balls in the basket now, and there are 4 blue balls, so the probability of catching the blue ball for the first time is (4/10); for the second catch, there are 9 left after the first one is removed. There are 2 green balls in the first ball, so the probability of catching the green ball is (2/9); for the third catch, the first and second balls are removed, and there are 8 balls and 3 green balls left. A blue ball, so the probability of catching the blue ball is (3/8), and the probability of catching the ball three times is multiplied together, so choose D