Question

Presume we have this sack of marbles. There are 4 green marbles, 3 red marbles, 2 blue marbles, and 1 yellow marble.

What is the probability of pulling a red marble, given a blue marble was pulled before without replacement?

Answer 1

There is a 33.3% chance you will pull a red marble after pulling a blue one.

Explanation:

There are a total of 10 marbles in the sack. A blue marble is removed from the bag without being replaced, leaving 9 in the sack. 3 of the marbles left are red. To find the probability of pulling a red marble, we divide the number of red marbles by the number of total marbles.

3/9 = 1/3 = 0.333 = 33.3%