500
A special lottery is to be held to select the student who will live in the only deluxe room in a dormitory. There are 100 seniors, 150 juniors, and 200 sophomores who applied. Each senior's name is placed in the lottery 3 times; each junior's name, 2 times; and each sophomore's name, 1 time. What is the probability that a senior's name will be chosen?
(A) 1 over 8
(B) 2 over 9
(C) 2 over 7
(D) 3 over 8
(E) 1 over 2
what is
(D) 3 over 8