The average of 20 numbers is zero Of them at the most how many may be greater than zero ...

The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ?

Average of 20 numbers = 0. 
Sum of 20 numbers = (0 * 20) = 0.
It is quite possible that 19 of these numbers may be positive and if their sum is a, then 20th number is (- a)

By: MIRZA SADDAM HUSSAIN