The 40-hour work week did not become a US. standard until 1940. Today, many white- collar employees work more than 40 hours per week. A random sample of 14 white-collar employees was obtained and the number of hours each worked during the last week was collected. The sample mean number of hours worked for the week was found to be 44.39 with a standard deviation of 3.38. a) Construct and interpret a 95% condence interval for the true mean number of hours worked each week by white-collar workers. (5 points) b) What conditions must be satised for the interval obtained in part (a) to be statistically valid? (2 points)