The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?
0
1
10
19
Explanation:
Average of 20 numbers = 0.
$\therefore$ Sum of 20 numbers $\left(0 \times 20\right)$ = 0.
It is quite possible that 19 of these numbers may be positive and if their sum is $ a $ then 20th number is $\left(- a \right)$.