Question

Box A contains two red cards and one black card, and box B contains one red card and two black cards. An experiment consists of randomly selecting one card from Box A and placing the selected card into Box B. Then, one card is selected from Box B. What is the probability that a red card is selected from Box B?

Answer 1

Answer: 5/12

Explanation:

Box A: 2 Red

1 Black

Box B: 1 Red

2 Black

One card is selected from Box A and placing the selected card into Box B.

One card is selected from Box B.

What is the probability that a red card is selected from Box B?

Two things can occur:

1) Select red from A and B:

2/3 * 2/4 = 1/3

2) Select black from A and red from B:

1/3 * 1/4 = 1/12

As 1) or 2) can occur:

1/3 + 1/12 = 5/12