The average of 20 number is zero of them at the most, how many may be greater than zero ?	Pick.
A) 0  B) 1  C) 10  D) 19  E) 20

Rationale: solution average of 20 numbers = 0 . ∴ sum of 20 numbers = ( 0 × 20 ) = 0 . it is quite possible that 19 of these number may be positive and if their sum is a , then 20 th number is ( - a ) . answer d
Answer: D