# 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:
79 comments Page 1 of 8.

Kumar said:   7 months ago
2.5 = 2 + 1/2 = 5/2
8 × 5/2 = 20,
65 + 20 = 85.
(5)

Ozzalll said:   1 year ago
Simple formula.

Weight Of replcae +- (increase/decrease)* number.
(7)

Iman said:   1 year 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.
(1)

Hemanjali T said:   3 years ago
Can you guys tell me about what happens if the weight is decreased by 2.5 kg? Please explain.

GAGAn said:   3 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.
(12)

Chitti said:   4 years ago
By using formula,
a = r+nx ------>
r = Removed value.
n = Number of persons.
x = Change in avg.

So,
a = 65+8(2.5).
a = 85 is new person weight.
(7)

Saravanan said:   4 years ago
Let x be an average of 8 persons.
Let y be the weight of the new person.
(x+y-65)/8 = (x/8)+2.5,
x+y-65 = x+20,
y-65 = 20,
y = 85.
(2)

Fahad Riaz said:   5 years ago
Total weight of 8 persons is 520 (65*8).
Now, a total weight of 7 persons is 455 (520-65),
Now try every option to get 2.5% increase,
(455+85)/8 is equal to 67.5,
The total increase is 2.5 KG (67.5-65),
Ans is 85 KG.
(1)