Question

An 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

(50/58)*(49/57)*(48/56) = 0.635
63.5%

Answer 2

number of all possible selections = C(58,3) = 30856
number of error-less selections = C(50,3) = 19600

prob to select non-error = 19600/30856 = 4900/7714
= 350/551

Answer 3

Go with drwls method, his is more direct.

Answer 4

find the probability of tossing 5 tails, then 5heads, on the 10 tosses of a fair coin