SAT Question of the Day #27

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.  1/8

B. 2/9

C. 2/7

D. 3/8

E. 1/2

 

The answer is:    D   3/8

How do you get to the answer:  To determine the probability that a senior’s name will be chosen, you must determine the total number of seniors’ names that are in the lottery and divide this number by the total number of names in the lottery. Since each senior’s name is placed in the lottery 3 times, there are 3 times 100 = 300 seniors’ names. Likewise, there are 2 times 150 = 300 juniors’ names and 1 times 200 = 200 sophomores’ names in the lottery. The probability that a senior’s name will be chosen is 300 over (300 + 300 + 200) = 300 over 800 = 3 over 8