A supermarket manager analysed the number of days absent per year for a random sample of 29 cashiers. Assume that days absent are normally distributed.
(a) Compute the mean (average) and standard deviation of days absent for the sample of 29 cashiers using the Descriptive Statistics option in Data Analysis. Interpret these sample findings for the manager.
(b) Estimate, with a 95% confidence level, the mean number of days absent per year for all supermarket cashiers. (Hint: Tick the Confidence Level for Mean box in Descriptive Statistics).
(c) If it is company policy that the average absenteeism level should not exceed 10 days per cashier per year, based on a 95% confidence level, is the company's policy being adhered to? Comment.
(d) Re-compute and confirm the 95% confidence limits using the TINV formula to find the t-limits.