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?
Answer: Option
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:
84 comments Page 1 of 9.
Mariam said:
2 decades ago
65 is the weight of only 1 of the 8 persons. Then how can you take it as d weight of all d persons?
Anonymous said:
1 decade ago
@ Mariam: Let x be the average weight
First case: Sum of weights of people / 8 people = x
So the sum of weights of people = 8x
Second case: Sum of weights of people / 8 people = x + 2.5
So the sum of weights of people here is 8(x + 2.5) = 8x + 20
So the difference between both sums is essentially the new heavier person that was added which is:
8x + 20 - 8x = 20
So the new guy weights 20kg more than the old guy.
So new guy weights: 65 + 20 = 85kg
First case: Sum of weights of people / 8 people = x
So the sum of weights of people = 8x
Second case: Sum of weights of people / 8 people = x + 2.5
So the sum of weights of people here is 8(x + 2.5) = 8x + 20
So the difference between both sums is essentially the new heavier person that was added which is:
8x + 20 - 8x = 20
So the new guy weights 20kg more than the old guy.
So new guy weights: 65 + 20 = 85kg
Riya said:
1 decade ago
Thank you. I was confused earlier. Your explanation has cleared it all. :).
Aparna said:
1 decade ago
Oral method:.
When the replaced persons weight was 65 kg then no effect takes place.
But due to him all of thems weight has been increased by 2.5kg.
So,
8*2.5=20.
65+20=85.
When the replaced persons weight was 65 kg then no effect takes place.
But due to him all of thems weight has been increased by 2.5kg.
So,
8*2.5=20.
65+20=85.
Vinoth M said:
1 decade ago
When a new person weight is added to 8 peoples weight each person weight is increased by 2.5%
Then weight increased is 8*2.5=20
So the new person age is 65+20=85
Then weight increased is 8*2.5=20
So the new person age is 65+20=85
Aamir said:
1 decade ago
A new person's weight is 65 kg and why add early 8 person, where as he is a replaced person.
Tinku said:
1 decade ago
@Aamir
It is not weight of the new person. It is weight of which person who is replace from the new person.
Let weight of new person is = x.
Replace person weight=65kg.
Total person=8.
Let total weight 8 person is W.
Before replace of a person.
W/8=a.
Here the a is the average.
Now replace a person which weight is 65kg.
(x+W-65)/8=a+2.5.
Put w=8a from above eqn.
Wet get x=85kg.
It is not weight of the new person. It is weight of which person who is replace from the new person.
Let weight of new person is = x.
Replace person weight=65kg.
Total person=8.
Let total weight 8 person is W.
Before replace of a person.
W/8=a.
Here the a is the average.
Now replace a person which weight is 65kg.
(x+W-65)/8=a+2.5.
Put w=8a from above eqn.
Wet get x=85kg.
Bhanu said:
1 decade ago
Hai Friends.
Try this method.
New person weight =Replaced person weight+ (no. Of persons*increased weight).
Replaced person weight =65.
No. Of persons =8.
Increased weight =2.5.
These all values are replaced in the formula, then we get the answer "85".
Try this method.
New person weight =Replaced person weight+ (no. Of persons*increased weight).
Replaced person weight =65.
No. Of persons =8.
Increased weight =2.5.
These all values are replaced in the formula, then we get the answer "85".
(1)
Isha said:
1 decade ago
Thanks bhanu your method is so good.
Kumar said:
1 decade ago
Here we are replacing the person of 65kg, then how 2. 5kg will effect to replaced person.
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