Suppose you own a plumbing repair business and employ 15 plumbers. You are interested in estimating the difference in the average number of calls completed per day between two of the plumbers. A random sample of 40 days of plumber A’s work results in a sample average of 5.3 calls, with a population variance of 1.99. A random sample of 37 days of plumber B’s work results in a sample mean of 6.5 calls, with a population variance of 2.36. Use this information and a 95% level of confidence to estimate the difference in population mean daily efforts between plumber A and plumber B. Interpret the results. Is it possible that, for these populations of days, the average number of calls completed between plumber A and plumber B do not differ?