Aptitude - Average - Discussion

Thanks for all of your explanations.

Is there any shortcut to find the answer for this question?

@Prabhat.

Your explanation was good, I got it now. Thank you.

To get a value zero we can use,
(Sum of 19 positive numbers) - (-Value of sum)/(Sum of 18 positive numbers) - (Value of sum),
Here, the maximum probability of positive number is 19 (at most),

So the answer is 19.

19 will be appropriate answer.

Because in the question, it is mention that maximum number greater than zero.
If we take all positive number then sum will never be 0.

So, at least one number should be taken negative that should be equal to the sum of the 19 numbers.

So, (1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1+ 1) + (-19) /20.

I hope you got it.

Hi,

In this question, they are asking about the number which is at most (it means maximum numbers which are greater than 0).

So, (1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1+ 1) + (-19) /20.

I hope you got it.

What about the answer if the question would be, "The average of 20 numbers is zero. Of them, at least, how many may be greater than zero"?

1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1+ 1 + 1 + 1 + 1 + 1 - 19 = 0.

+ve numbers are 19, So, D is the answer.

The question is not very rigorous but the main adversity of this question is that answer is 19 because in the question only asking that the no. an average of only 20 numbers is zero not asking that 1 to 20 numbers is zero so the 20 = 0 and 0<19 value. i.e 1, 2, 3, 4, 5, 6, 6, 7, 8, 9. 19.

The question is rhetoric, at the first glance it looks like well calculated but actually it requires analytical skill. Let's see.

Our average should be 0 and the total number is 20. Hence, we should understand that dividing by 20, if we have 20 then it will be 1.

If we have more than 20 then it will be more than 1 and the most crucial is that it will never be 0.
Then what can be more than 1, and it can be less than 20 so that we can avoid 1.

Therefore 19/20 =. ___ <1.