A IRS auditor randomly selects 3 tax returns from 42 returns of which 15 contain errors. What is the probabilitythat none of the returns she selects contains an error?
A) 0.2548
B) 0.2657
C) 0.0456
D) 0.0396

Question

Quizplus · Accepted Answer

The probability that none of the returns selected contains an error can be calculated using combinations. There are 27 returns without errors out of 42. The probability is the number of ways to choose 3 returns from the 27 without errors divided by the number of ways to choose 3 returns from all 42. This is calculated as (27 choose 3) / (42 choose 3) = (27! / (24! * 3!)) / (42! / (39! * 3!)) ≈ 0.2548.

A IRS Auditor Randomly Selects 3 Tax Returns from 42