試題詳解

224. A large university will begin a 13-day period during which students may register for that semester’s courses. Of those 13 days, the number of elapsed days before a randomly selected student registers has a continuous distribution with density function f(t) that is symmetric about t = 6.5 and proportional to 1/(t + 1) between days 0 and 6.5.

A student registers at the 60th percentile of this distribution.

Calculate the number of elapsed days in the registration period for this student.
(A) 4.01
(B) 7.80
(C) 8.99
(D) 10.22
(E) 10.51