Problem Solving

[GMAT math practice question]

If the average of five positive integers is 16, and the largest of the integers is 40, then the median of the five integers could be which of the following?

I. 10
II. 15
III. 20

A. I only
B. II only
C. III only
D. I & II only
E. I, II & III only

=>

Since the average of the five positive integers is 16, their sum is 5*16 = 80. So, the four smallest numbers must sum to 80 - 40 = 40.

As the integers are positive, the smallest possible median occurs if the integers are 1,1,1,37 and 40. The largest possible median occurs if the third and fourth integers are as large as possible. For this to occur, the two smallest integers must be as small as possible, that is, 1 and 1. In this case, the two remaining integers add to 40 - (1 + 1) = 38. The largest possible median occurs if the two remaining integers are equal to 38/2 = 19. Therefore, the median lies between 1 and 19, inclusive. So, 20 is not the median.

If the numbers are 1,1,10,28 and 40, the median is 10, and if the numbers are 1,1,15, 23 and 40, the median is 15.

Therefore, the answer is D.

Answer: D