The operations manager of a large production plant would lik

The operations manager of a large production plant would like to estimate the average amount of time workers take to assemble a new electronic component. After observing a number of workers assembling similar devices, she guesses that the standard deviation is 6 minutes. How large a sample of workers should she take if she wishes to estimate the mean assembly time to within 23 seconds. Assume the confidence level to be 98%.

Solution

Given a=1-0.98=0.02, Z(0.01) =2.33 (from standard normal table)

24 seconds = 24/60 =0.4 minutes

So n=(Z*s/E)^2

=(2.33*6/0.4)^2

=1221.502

Take n=1222