The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?
1). 0
2). 1
3). 10
4). 19
Given that average of 20 numbers = 0
Average of 20 numbers = (sum of 20 numbers) /20
⇒ 0 = (sum of 20 numbers)/20
∴ Sum of 20 numbers = 0
Let the sum of 19 positive numbers = q
In order to become sum = 0, 20th number must be equal to (-q)
∴ At most 19 numbers can be greater than zero