A bag contains 5 white, 7 red and 3 black balls. If three balls are drawn one by one without replacement, find the probability that none is red.

Explanation

There are total `15` balls and red balls are `7`.

`:.` Probability that first ball is not red `= 8/15`.

Now, there are `14` total balls and `7` balls are not red.

`:.` Probability of drawing second ball that is not red `= 7/14 = 1/2`

Now, there are `13` total balls and `6` balls are not red.

`:.` Probability of drawing third ball that is not red `= 6/13`

`:.` Required probability `= 8/15**1/2**6/13 = 8/65 `