When average age of 21 members are 0, how many members greater than 0?
Options:
A) 17
B) 20
C) 21
D) 24
E) 25

Rationale: "average of 21 numbers = 0 . sum of 21 numbers ( 0 x 21 ) = 0 . it is quite possible that 20 of these numbers may be positive and if their sum is a then 21 st number is ( - a ) answer is 20 ( b )"
Answer: B