An instructor wanted to determine if chocolate would impact students' performance in beginning statistics. He randomly assigned half the class to Group A and the other half to Group B. Group A received chocolate wile Group B did not receive any chocolate. At the end of the semester, the instructor administered the final exam. The results were as follows:

Group A Group B

(chocolate) (no chocolate)

n = 30 n = 30

Mean=77 Mean = 72

Variance = 15 Variance = 17

Research Question: Do those students that received chocolate perform better than those that did not receive chocolate? Use the .05 level of significance to test the null hypothesis.

a. H_o: _______________________________________________________

b. H_a: _______________________________________________________

c. Appropriate statistical test:

(indicate type, one or two sample, one or two tail, df)

_______________________________________________________

d. Critical region for rejection of the null hypothesis:

____________________________________________________________

e. The result from the statistical test is 4.85.

What is your decision about null hypothesis?

____________________________________________________________

f. Compute Cohen's d effect size for this study (feel free to use an online calculator)

g. Verbal Conclusions: