Question

The quality control manager at a computer manufacturing company believes that the mean life of a computer is 105 months, with a variance of 81 If he is correct, what is the probability that the mean of a sample of 70 computers would differ from the population mean by less than 1.9 months? Round your answer to four decimal places.

Answer 1

Answer 2

The solution above is not complete. The complete soltion is to consider both side of (-1.77 and +1.77) if you really read the question it says the probability differ from the mean and mean has two sides.