Question

A irs auditor randomly selects 3 tax returns from 58 returns of which 8 contain errors. what is the probability that she selects none of those containing errors?

Answer 1

There are 58 – 8 = 50 returns with no errors.

There are 58 * 57 * 56 / 1 * 2 * 3 = 1110816 possible sets of 3 returns that the auditor could pick.

Of those 50 * 49 * 48 / 1 * 2 * 3 = 705600 are sets of 3 returns with no errors,.

The number of possible sets of 3 returns with no errors as a fraction of the number of possible sets of 3 returns available for auditing is:

50 x 49 x 48 / 58 x 57 x 56 = about .647

So the probability is computed is 64.7/100 = 64.7%