Each state has two Senators. Suppose we were interested in studying the age differences between the Senators. That is, we would like to know if the more recently elected Senator also tends to be younger in age. (For example: In California, the longer-serving Senator is currently Dianne Feinstein, age 87, and the junior Senator is Alex Padilla, age 48.)

If you were studying Senators from all 50 states, what type of hypothesis test would you perform to address this question?