Aptitude - Average - Discussion

Average = Weights /number of members.

So,
Weights = Average * number of members.

If the Average increased by 2.5, then:
Weights will increase by (2.5 * 8) = 20.

Increase in weights = 20 kg,
The new person's weight = 65 + 20 = 85 kg.

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.

Here;
2 +1/2 Means 5/2.
a = 65+8* 5/2.
a = 85 is the new person's weight.

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.

2.5 = 2 + 1/2 = 5/2
8 × 5/2 = 20,
65 + 20 = 85.

Simple formula.

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

@Manoj Kumar.

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

@Tinku.

Thanks for your explanation.

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.

Can you guys tell me about what happens if the weight is decreased by 2.5 kg? Please explain.