What is the minimum percentage increase in the mean of set S {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?	Choose the correct choice from the following answers
A) 25 %	B) 50 %	C) 75 %	D) 100 %	E) 200 %

Rationale: mean of s is ( - 4 - 1 + 0 + 6 + 9 ) / 5 = 2 ; in order the increase to be minimal we should replace two smallest elements of s , which are - 4 and - 1 , with two smallest primes , which are 2 and 3 . hence our new set will be { 2 , 3 , 0 , 6 , 9 } - - > new mean is ( 2 + 3 + 0 + 6 + 9 ) / 5 = 4 . percent increase = ( 4 - 2 ) / 2 * 100 = 100 % . answer : d .
Answer: D