9.40 Medical research has shown that repeated wrist extensions beyond 20 degrees increase the risk of wrist and hand injuries. Each of 24 students at Cornell University used a proposed new computer mouse design, and while using the mouse, each student’s wrist extension was recorded. Data consistent with summary values given in the paper “Comparative Study of Two Computer Mouse Designs” (Cornell Human Factors Laboratory Technical Report RP7992)

are given here.

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a. Use these data to estimate the mean wrist extension for people using this new mouse design using a 90% confidence interval.

b. Are any assumptions required in order for it to be appropriate to generalize your estimate to the population of Cornell students? To the population of all university students?

c. Based on your interval from Part (a), do you think there is reason to believe that the mean wrist extension for people using the new mouse design is greater than 20 degrees? Explain why or why not.