13. A 21-year old college student submits a photo to the website "Guess My
Age". At a later date he checks back and thousands of users have made
guesses about his age. Of the following, which is the best procedure to
investigate whether there is convincing statistical evidence that, on average, he
is perceived to be less than 21 years old?
(A) One sample t-test for a mean
(B) One sample z-test for a proportion
(C) Matched-pairs t-test for a mean difference
(D) Two-sample t-test for the difference between two means
(E) A chi-square test of association