Question

1. We want to test to see whether average SAT scores for science majors equals the average SAT scores for non-science majors. We collect the following sample SAT scores:

Science            Non-Science

440                  1000

1550                1010

1400                970

370                  1020

600                  980

800                  1000

1390                1080

1100   

1500   

1480   

450     

1430

Use Excel to test this hypothesis at the 0.05 level by first testing variances (at the 0.05 level) and then means

Answer 1

First to test the equality of two variances,

using excel, Data -> Data Analysis -> F -Test Two sample for variances, we get the following output :

Since P-value = 0.0000013022 < 0.05, so at 5% level of significance we reject the null hypothesis and we can conclude that the two variances are significantly different.

Now, to test the two means using t test for unequal variances,

using excel, Data -> Data Analysis -> t-Test: Two-Sample Assuming Unequal Variances, we get the following output :

Since P-value = 0.81 > 0.05, so so at 5% level of significance we fail to reject the null hypothesis and we can conclude that average SAT scores for science majors for non-science majors are not significantly different.