85. Employee athletes. An ergonomics consultant is engaged by a large consumer products company to see what they can do to increase productivity. The consultant recommends an “employee athlete” program, encouraging every employee to devote 5 minutes an hour to physical activity.

The company worries that the gains in productivity will be offset by the loss in time on the job. They’d like to know if the program increases or decreases productivity. To measure it, they monitor a random sample of 145 employees who word process, measuring their hourly key strokes both before and after the program is instituted. Here are the data:

a) What are the null and alternative hypotheses?

b) What can you conclude? Explain.

c) Give a 95% confidence interval for the mean change in productivity (as measured by keystrokes per hour).

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Keystrokes per Hour Before After Mean 1534.2 1556.9 Difference (After - Before) 22.7 SD 168.5 149.5 113.6 N 145 145 145