Question: Children in two elementary school classrooms were given two versions of the same test, but with the order of questions arranged from easier to more difficult in Version A and in reverse order in Version B. Randomly selected students from each class were given Version A and the rest Version B. The results are shown in the table.
a. Construct the 90% confidence interval for the difference in the means of the populations of all children taking Version A of such a test and of all children taking Version B of such a test.
b. Test at the 1% level of significance the hypothesis that the A version of the test is easier than the B version (even though the questions are the same).
c. Compute the observed significance of the test.