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 Aand 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.
Version A 31 83 4.6
Version B
32 78 4.3
(a) A 90% confidence interval for the difference in the means of the populations
5 ± 1.85
5 ± 0.53
5 ± 1.12
5 ± 1.44
5 ± 0.87
(b) At the 1% significance level, will you conclude that the A version of the test is easier than the B version (even though the questions are the same)?
The test statistic is z=4.42; reject the null hypothesis
The test statistic is z=4.45; reject the null hypothesis
The test statistic is z=9.4; reject the null hypothesis
The test statistic is z=4.42; fail to reject the null hypothesis
The test statistics is z=4.45; fail to reject the null hypothesis