Question

A bag contains 5 red discs and 4 blue discs. If 3 discs are drawn from the bag without
replacement, then find the probability that
(i) all three are blue
(ii) there are 2 red and 1 blue
(iii) the second disc is red.
n​

Answer 1

Answer:

here it is

Step-by-step explanation:

The easiest way as to solve this is to calculate the opposite … the probability that none of the discs selected are white. Then, the probability that at least one of them is white will be 1 minus the probability that none are white.

The colors are irrelevant. There are 15 disks , of which 2 are white.

The probability that the first disk selected is not white is 13/15.

The probability that the second disk selected is then not white is 12/14 (14 remain, of which 2 are white).

The probability that the third disk selected is not white is 11/13 (13 remain, of which 2 are white).

So, to calculate the probability that no white disks are drawn, we multiply the three probabilities:

Probability that no white disks are selected = 13/15 x 12/14 x 11/13 = 1716/2730 = 0.629 or 62.9%.

So, the probability that at least one white disk is selected = 1 - 0.629 = 0.371 or 37.1%.