Question

Two urns contain white balls and yellow balls. The first urn contains 3 white balls and 6 yellow balls and the second urn contains 3 white balls and 8 yellow balls. A ball is drawn at random from each urn. What is the probability that both balls are white?

Answer 1

We have 3 white balls in the first urn out of 9. That means we have a 1 in 3 chance at picking the white ball in the first urn.

Now, we have a 3 in 11 chance at picking the white ball in the second urn.

Since, we want them simultaneously, we need to multiply them.

1/3 × 3/11 = 1/11 chance