SOLUTION: An IRS auditor randomly selects 3 tax returns from 61 tax returns of which 9 contain errors. What is the probability that she selects all those containing errors? This is unusual p

Algebra ->  Probability-and-statistics -> SOLUTION: An IRS auditor randomly selects 3 tax returns from 61 tax returns of which 9 contain errors. What is the probability that she selects all those containing errors? This is unusual p      Log On


   

Question 1153209: An IRS auditor randomly selects 3 tax returns from 61 tax returns of which 9 contain errors. What is the probability that she selects all those containing errors? This is unusual probability?
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!
An IRS auditor randomly selects 3 tax returns from 61 tax returns of which 9 contain errors. What is the probability that she selects all those containing errors? This is unusual probability?
----------------------------
An IRS auditor randomly selects 3 tax returns from 61 tax returns of which 9 contain errors. What is the probability that she selects +cross%28all+those%29 +green%28three%29+ containing errors? This is unusual probability? 


(9/61)*(8/60)*(7/59) = 504/215940 = 0.00233



I wouldn't call the probability "unusual."   Perhaps better is to say there is a very low probability (or, the event is highly unlikely).   If she repeated the process 1000 times, only about twice will she select three errored returns.