Sample of Final Exam scores from two statistics classes with different instructors provided the following results:
Instructor A Instructor B
n1 = 12 n2 = 15
x1 = 72 x2 = 79
s1 = 8 s2 = 10
Using a = .05, test whether these data are sufficient to conclude that the population mean grades differ for the two instructors.
First we need to develop the null and alternative hypothesis.
Ho : µ1 – µ2 = 0
Ha : µ1 – µ2 0 and we will reject Ho if p < .05
For this problem we will use a T-test. Start from the “TESTS” menu.
Press Arrow right to "TESTS" and Arrow down to "4 : 2-SampTTest..."
Press (see screen below )
Choose "Stats" and press
Next, match the settings on your calculator to those on the above screen.
Be sure you highlight the alternative test "".
Now we need to calculate the F Test statistic.
F = 102 Ö 82 = 100 / 64 = 1.5625
Again we can assume equal variances so highlight "Yes".
Arrow down to "Calculate" and press (see screen below)
In conclusion we must say that at the alpha = .05 level there is not sufficient evidence to claim that the mean test scores between the two instructors differ.