Chapter 9.5, Problem 115E

Preliminary data analyses indicate that you can reasonably use a t-test to conduct each of the hypothesis tests required in Exercises 9.113–9.118.

9.115 Death Rolls. Alligators perform a spinning maneuver, referral to as a “death roll,” to subdue their prey. Videos were taken of juvenile alligators performing this maneuver in a study for the article “Death Roll of the Alligator, Mechanics of Twist and Feeding in Water” (Journal of Experimental Biology, Vol. 210, pp. 2811–2818) by F. Fish et al. One of the variables measured was the degree of the angle between the body and head of the alligator while performing the roll. A sample of 20 rolls yielded the following data, in degrees.

At the 5% significance level, do the data provide sufficient evidence to conclude that, on average, the angle between the body and head of an alligator during a death roll is greater than 45°? (Note: $\bar{x}$ = 49.0 and s = 10.0)