Carcass wrote:
A set has exactly five consecutive positive integers starting with 1. What is the percentage decrease in the average of the numbers when the greatest one of the numbers is removed from the set?
(A) 5
(B) 8.5
(C) 12.5
(D) 15.2
(E) 16.66
The original average = (1 + 2 + 3 + 4 + 5)/5 = 3.
The new average = (1 + 2 + 3 + 4)/4 = 2.5
(2.5 - 3)/3 x 100 = -0.5/3 x 100 = -1/6 x 100 ≈ -16.7
We see that the average is decreased by approximately 16.7%.
Answer: E