13.49 For each of the following situations, identify whether the appropriate test is a paired t-test or a two-sample t-test:

a. The weights of a sample of 15 marathon runners were taken before and after a training run to test whether marathon runners lose dangerous levels of fluids during a run.

b. Random samples of 200 new freshmen and 200 new transfer students at a university were given a 50-question test on current events to test whether the level of knowledge of current events differs for new freshmen and transfer students.