SOLUTION: 17) Among the 25 invoices prepared by a billing department, 5 contain errors while the others do not. If we randomly check 3 of these invoices, what are the probabilities that a.

Algebra ->  Probability-and-statistics -> SOLUTION: 17) Among the 25 invoices prepared by a billing department, 5 contain errors while the others do not. If we randomly check 3 of these invoices, what are the probabilities that a.       Log On


   

Question 870422: 17) Among the 25 invoices prepared by a billing department, 5 contain errors while the others do not. If we randomly check 3 of these invoices, what are the probabilities that
a. All three will contain errors
b. Neither will contain errors
c. At least one will contain errors
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
p(errors) = 5/25 = 1/5 = .2, n = 3 (check 3)
a) P(all contain errors) = (.2)^3
b) P(none contain errors) = (.8)^3
c) P(at least one) = 1- P(none) = 1-(.8)^3