Choose a test for each situation: one-sample t-test, two-sample t-test, paired t-test, and no t-test.

a. A random sample of students who transfered to a 4-year university from community colleges are asked their GPAs. Our goal is to determine whether the mean GPA for transfer students is significantly different from the population mean GPA for all students at the university.

b. Students observe the number of office hours posted for a random sample of tenured and a random sample of untenured professors.

c. A researcher goes to the parking lot at a large grocery chain and observes whether each person is male or female and whether they return the cart to the correct spot before leaving (yes or no).