In the study referred to in Exercise 7.13, Katz et al XXXXXXXXXXcompared the performance on SAT items of a group of 17 students who were answering questions about a passage after having read the...

In the study referred to in Exercise 7.13, Katz et al. (1990) compared the performance on SAT items of a group of 17 students who were answering questions about a passage after having read the passage with the performance of a group of 28 students who had not seen the passage. The mean and standard deviation for the first group were 69.6 and 10.6, whereas for the second group they were 46.6 and 6.8.

a. What is the null hypothesis?

b. What is the alternative hypothesis?

c. Run the appropriate t test.

d. Interpret the results.