Question

An employer wants to estimate to set a time limit so that 75% of the employees will finish a job on time. Past history has shown that the time required to do the job is normally distributed and has a mean time of 26 minutes with a standard deviation of 5 minutes. How much time should the employer allow employees to finish the job? Round to the nearest minute. Show work.

Answer 1

Use a z-score formula:

z = (x - mean)/sd

Find the z-score that corresponds to 75% using a z-table. Remember that this value will be a positive z-score and above the mean of the distribution. Substitute z, mean, and sd given in the problem, then solve for x.

I hope this will help get you started.