Suppose you give a random sample of students a questionnaire about extraversion, and some (10) are classified as extraverts and some (15) as not extraverts. You want to determine whether the typical GPA is higher for extraverts than for those who are not extraverts. Which test(s) can be used for each situation below?

a. Both distributions are strongly skewed. 

b. Both distributions are nearly Normal.

c. You have 100 extraverts and 150 who are not extraverts, and both distributions are skewed. Explain your choice of test.

Choose from the following tests, as appropriate: paired t-test, sign test, two-sample t test, and Mann-Whitney test. There may be two acceptable choices.