(Two-Sample t-Test Assuming Equal Variances) The test scores on the same algebra test were recorded for eight students randomly selected from students taught by Teacher A and nine students randomly selected from students taught by Teacher B. Is there a difference in the average scores for students taught by these two teachers?

1. Select stat ➤ EDIT and enter the data into lists L1 and L2. Use stat ➤ CALC ➤ 1:1-Var Stats to find the standard deviations for the two samples, s 59.91 1 and s 58.80 2 . Since the ratio of the two variances is s /s 51.27 1 2 2 2 (less than 3), you are safe in assuming that the population variances are the same.
2. Use stat ➤ TESTS ➤ 4:2-SampTTest and select Data in the “Inpt:” line. Make sure that lists L1 and L2 are selected and that the alternative hypothesis is m ?m 1 2.
Select “Yes” on the line marked “Pooled.” When you move the cursor to Calculate and press enter, the results will appear, a portion of which is shown on the screen in Figure 10.30(a). With t520.03 and p-value50.974, the results are not significant.
Similar commands will allow you to calculate a (12a)100% two-sided confidence interval using stat ➤ TESTS ➤ 0:2-SampTInt

Transcribed Image Text:

Teacher A 65 88 93 95 80 76 79 77 Teacher B 91 85 70 82 92 68 86 87 75