Question

The human resources department of a consulting firm gives a standard creativity test to a randomly selected group of new hires every year. This year, 65 new hires took the test and scored a mean of 112.9 points with a standard deviation of 16.5. Last year, 60

new hires took the test and scored a mean of 117.1 points with a standard deviation of 19.2. Assume that the population standard deviations of the test scores of all new hires in the current year and the test scores of all new hires last year can be estimated by the sample standard deviations, as the samples used were quite large. Construct a 90% confidence interval for −μ1μ2, the difference between the mean test score μ1 of new hires from the current year and the mean test score μ2 of new hires from last year. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places. (If necessary, consult a list of formulas.)

What is the lower limit of the 90% confidence interval?
What is the upper limit of the 90% confidence interval?

Answer 1