Question

A bag contains 8 white and 3 black counters. Two counters are drawn, one after the other. Find the probability of drawing one white and one black counter, in any order. i) If the first counter is replaced ii) if the first counter is not replaced.

Answer 1

White = 8/11

Black = 3/11

1) If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.

P(BW) = 3/11 * 8/11

P(WB) = 8/11 * 3/11

Either-or probabilities are found by adding the individual probabilities.

2) P(BW) = 3/11 * 8/(11-1)

P(WB) = 8/11 * 3/(11-1)