Question

A bag has 4 green marbles, 3 red marbles, and 3 yellow marbles. What is the probability that you pick a green marble, do not replace it, and pick a red marble?

Answer 1

1/10

Explanation:

Assuming there are 3 red marbles:

3/10 × 3/9 = 9/90 = 1/10

There are 3 red, that is where the first numerator comes from and there are 10 marbles so that is where the denominator comes from. There are 3 yellows, hence the second numerator but as we have taken a marble out there are now only 9 marbles in total.

Answer 2

4/10 chances to pick a green marble and 3/10 to pick a red marble