Urn A has balls numbered 1 through 7. Urn B has balls numbered 1 through 5. A ball is selected at random from urn A and then a ball is selected at random from urn B. What is the probability that a 4 is drawn from A followed by a 2 from B?

Answer 1

Pa(4) = 1 ball out of 7
Pb(2) = 1 ball out of 5

Probability that both events will happen is the product of the two probabilities.

Answer 2

1/35