1. probability

a bag contains 8 white counters and 3 black counters. 2 counters are drawn, one after the other. find the probability of picking 1 white counter and 1 black counter if the 1st counter is
a) replaced

b) not replaced

2. Originally Posted by si55ler
a bag contains 8 white counters and 3 black counters. 2 counters are drawn, one after the other. find the probability of picking 1 white counter and 1 black counter if the 1st counter is
a) replaced

b) not replaced
a).You have 11 counters in all. The probability of choosing a white on the first draw is 8/11.
If you put it back, the probability of then picking a black is 3/11.

b). The probability of choosing a white from the bag on the first draw is 8/11.
If you don't replace it, that leaves 10 counters left in the sack.