# Aptitude - Average - Discussion

Discussion Forum : Average - General Questions (Q.No. 5)
5.
The average weight of 8 person's increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg. What might be the weight of the new person?
76 kg
76.5 kg
85 kg
None of these
Explanation:

Total weight increased = (8 x 2.5) kg = 20 kg.

Weight of new person = (65 + 20) kg = 85 kg.

Video Explanation: https://youtu.be/ceg2jvHsiJU

Discussion:
82 comments Page 1 of 9.

Bilawal F said:   3 months ago
Let's suppose Average age = 10
Age of sum of 8 ppl = 8×10 = 80
If age increases by 2.5 then = 12.5×8= 100,
Difference= 100-80 = 20.
New person age plus the difference of the ages of the first 8 ppl = 65+20,
= 85.
(1)

Ramu Bhandari said:   5 months ago
Here;
2 +1/2 Means 5/2.
a = 65+8* 5/2.
a = 85 is the new person's weight.
(1)

Mounika said:   9 months ago
Age of captain = 26 ...
So the age of the wicket-keeper who is 3 years older than the captain = 29
Let avg of 11 members be x, then
The sum of observations /11 = x.

I. e 26+29+ remaining sum of 9 members = 11x.
Remaining sum of 9 = 11x-55--->(1)
Given that, avg of the remaining 9 will be one less than the total average.
So total avg is x, then the of 9 is x-1.

I. e sum of remaining 9/9 = x-1.
Sum of remaining 9 = 9x-9 ----> (2)
9x-9 = 11x-55 from 1 and 2.

11x -9x = -9+55.
2x = 46,
x= 46/2 = 23.
(1)

Kumar said:   1 year ago
2.5 = 2 + 1/2 = 5/2
8 × 5/2 = 20,
65 + 20 = 85.
(5)

Ozzalll said:   2 years ago
Simple formula.

Weight Of replcae +- (increase/decrease)* number.
(17)

Iman said:   2 years ago
@Manoj Kumar.

Thanks for explaining. Your method is very helpful to solve the QA questions.

Abhi said:   2 years ago
@Tinku.

Bhavya sharma said:   3 years ago
Not able to understand.

Here you poised 20kg to this person's weight but not well 20kg should be added to all persons in one person's weight only 2.5kg should be added.

Am I right.
(2)

Hemanjali T said:   4 years ago
Can you guys tell me about what happens if the weight is decreased by 2.5 kg? Please explain.

GAGAn said:   4 years ago
Let the average was 10.

Then the sum of 8 people was 10*8 = 80.
When new person comes ,average was increased by 2.5 so new average is 12.5 the new sum = 12.5 * 8 = 100.

So the difference is of 20.
Now whoever new person he will increase the sum by 20 so new person weight is 65 + 20 =85 is the Answer.
(23)