Chapter 9, Problem 9.14TI

The mean throwing distance of a football for Marco, a high school freshman quarterback, is 40 yards, with a standard deviation of two yards. The team coach tells Marco to adjust his grip to get more distance. The coach records the distances for 20 throws. For the 20 throws, Marcos mean distance was 45 yards. The coach thought the different grip helped Marco throw farther than 40 yards. Conduct a hypothesis test using a preset a = 0.05. Assume the throw distances for footballs are normal.

First, determine what type of test this Is, set up the hypothesis test, find the p-value, sketch the graph, and state your conclusion.

[} Using the T1-83, 83+. 84, 84+ Calculator

Press STAT and arrow over to TESTS. Press l:Z-Test. Arrow over to Stats and press ENTER. Arrow down and enter 40 for p0 (null hypothesis), 2 for a. 45 for the sample mean, and 20 for n. Arrow down to p: (alternative hypothesis) and set it either as <, $\ne$ or >.. Press ENTER. Arrow down to Calculate and press ENTER. The calculator not only calculates the p-value but ft also calculates the test statistic (z-score) for the sample mean. Select <, $\ne$ or > for the alternative hypothesis. Do this set of instructions again except arrow to Draw (instead of Calculate). Press ENTER. A shaded graph appears with test statistic and p-value. Make sure when you use Draw that no other equations are highlighted In Y = and the plots are turned off.