Aptitude - Average - Discussion

Discussion Forum : Average - General Questions (Q.No. 4)
4.
The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?
0
1
10
19
Answer: Option
Explanation:

Average of 20 numbers = 0.

Sum of 20 numbers (0 x 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).

Discussion:
135 comments Page 9 of 14.

Sugi s said:   8 years ago
Thanks for your answer @Ravi.

Vignesh said:   8 years ago
For example : The Sum of first 19 number is 20 and the last number is -20. Therefore 20 -20 = 0.

Poonam said:   7 years ago
Thanks @Ravi.

Vignesh said:   7 years ago
1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1-19 = 0.
Therefore 0/20 =0.

Sai said:   7 years ago
@All.

Why we think only one no is negative, let we think maybe 10 numbers -ve; i.e 10 numbers less than zero and 10 numbers is +ve i.e 10 numbers greater than zero. so the avg of -10 numbers and +10 numbers is equal to zero.

Subash said:   7 years ago
@Sai.

In the question, they had given AT THE MOST.

So, the maximum value must be the answer.

Saikat said:   7 years ago
Please anyone help I can't understand this.

Habib said:   7 years ago
Thanks @Praveen.

Denis said:   7 years ago
How? Explain me the answer.

Ankit Dere said:   7 years ago
It is asked in the question.

Avg of 20 numbers is Zero,
Given avg=0.
Numbers=20.

Explanation:
Avg=sum÷number i.e.
0=sum÷20
Now, cross multiply.
Sum=20x0=0.
This means the sum of 20 numbers is equal to 0.
{1+2+...+20}= is 0.

{1+2+...+19}= Will not be 0.

But the sum of rest 19 number will not be 0 it will be greater than 0(as the 2nd part of the question says how many may be greater than 0?)
(5)


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