Aptitude - Average - Discussion

@ hema ...
see here the sum is zero ...
sum of 20 numbers has to be 0
ex: 1+2+3+4+5+6...+20 = 0
let 1+2+3+4+5...19=a and the 20th number should be '-a' in order to get the sum as zero .
(a(1st 19numbers)-a(last 20th munber)=0 , hence a-a=0)
hence all 1st 19 numbers are positive means greater than zero and the last 20th is negative .
hence answer is 19 positive i.e greater than zero numbers.

@ Jeeva.

In question it s asked numbers greater than 0, how negative nos be greater than 0. Negative no is less than 0.

Please try this:

Sum of 10 +ve no's + 10 -ve no's = 0

So, sum is zero.

The answer may be 20.

Hi Hema,

Here average of 20 numbers= 0.

So we have avg = sum/20.

That implies sum = 0.

Now for the sum of 20 numbers to be equal to zero, there may be all 19 numbers of them >0 and only one number which is -ve of all the 19 numbers sum.

So the answer is 19.

Hope you understood now.

All the best.

I don't unterstand this answer. Please any one explain.