Sample size needed to estimate mean Refer to the data in Problem 22-12 for Jupiter Corporation's production of differential assemblies. Management wants to estimate the mean of the population by analyzing a single random sample of 15 items. The population standard deviation is known to be 71.75.

REQUIRED a. Select a random sample of 15 items from the population and use it to estimate the mean and standard deviation of the population. b. Compute the magnitude of error that management can expect from the sample mean, using the population standard deviation and a 95 percent confidence limit. Then describe what the error means. c. Determine what sample size would have to be taken if management wants to be 95 percent certain that its estimate of the population means does not vary from the true mean by more than 30 units in either direction.