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 2 of 9.
Riddhi said:
8 years ago
It's said in question that avg increase by 2.5,
So we can say orginal average maybe X.
X+ 2.5 is avg of 8 people when a new person added instead of a man having 65 kg.
So Wat I meant is deviation is 2.5 or difference 2.5 ( avg b4 a new person was not added )---(Avg after a new person got added).
2.5*8 = 20 kg is the weight that is needed to be disturbed amongst 5 people to get avg of 2.5 so,
20+65 = 85kg.
So we can say orginal average maybe X.
X+ 2.5 is avg of 8 people when a new person added instead of a man having 65 kg.
So Wat I meant is deviation is 2.5 or difference 2.5 ( avg b4 a new person was not added )---(Avg after a new person got added).
2.5*8 = 20 kg is the weight that is needed to be disturbed amongst 5 people to get avg of 2.5 so,
20+65 = 85kg.
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.
Mukesh said:
1 decade ago
Old School method.
Let Z+65 be weight of 8 person and their average be A.
So, (z+65)/8 = A .......(i).
Now with the replacing the person with 65 KG weight with new person, average becomes A+2.5, let the weight of new person be x KG.
So, (Z+x/8) = A+2.5 .......(ii).
Subtraction (i) from (ii).
(x+65)/8 = 2.5.
Therefor, x = 85.
Let Z+65 be weight of 8 person and their average be A.
So, (z+65)/8 = A .......(i).
Now with the replacing the person with 65 KG weight with new person, average becomes A+2.5, let the weight of new person be x KG.
So, (Z+x/8) = A+2.5 .......(ii).
Subtraction (i) from (ii).
(x+65)/8 = 2.5.
Therefor, x = 85.
Anand said:
7 years ago
The average weight of three men 'X', 'Y' and 'Z' is 75 kgs. Another man 'A' joins
the group and the average weight now becomes 80 kgs. If another person 'B' whose
weight is 5 kgs more than 'A' replaces 'X', then the average weight of 'Y', 'Z', 'A' and
'B' will be 85 kgs. What is the weight of 'X'?
Can anyone solve this?
the group and the average weight now becomes 80 kgs. If another person 'B' whose
weight is 5 kgs more than 'A' replaces 'X', then the average weight of 'Y', 'Z', 'A' and
'B' will be 85 kgs. What is the weight of 'X'?
Can anyone solve this?
Anil Kumar Basam said:
9 years ago
Total 9 person's average weight = 65 -> So, 65*9 = 585.
Every person comes in the place increases 2.5 -> So, 65 - 2.5 = 62.5.
8 persons average weight = 62.5.
Sum of the elements = average*total numberof elements.
=> 62.5*8 =500.
Sum of 9 persons - sum of 8 persons = 585 - 500= 85.
New person weight = 85kg.
Every person comes in the place increases 2.5 -> So, 65 - 2.5 = 62.5.
8 persons average weight = 62.5.
Sum of the elements = average*total numberof elements.
=> 62.5*8 =500.
Sum of 9 persons - sum of 8 persons = 585 - 500= 85.
New person weight = 85kg.
Sarvesg said:
1 decade ago
The first line says average weight weight of person is increased by 2.5.
1) So the total weight increase is = 2.5*8 = 20.
2) Then it says when old person weighting 65 kg is replaced by new one since the weight increase is because of only one person add the old person weight+the average weight = 65+20 = 85.
1) So the total weight increase is = 2.5*8 = 20.
2) Then it says when old person weighting 65 kg is replaced by new one since the weight increase is because of only one person add the old person weight+the average weight = 65+20 = 85.
GAGAn said:
5 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.
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.
(25)
S S KUMAR said:
9 years ago
@NANDINI.
We are adding 20 to 65 because the average weight of 8 persons is being increased to 2.5 kg, by the new person who has been replaced by the existing one.
This directly implies that the new person who added into these will weigh more than the replaced one.
Hope you understand this.
We are adding 20 to 65 because the average weight of 8 persons is being increased to 2.5 kg, by the new person who has been replaced by the existing one.
This directly implies that the new person who added into these will weigh more than the replaced one.
Hope you understand this.
Anis said:
8 years ago
@Chitti.
Answer : 53 years.
(Sum of age of 12 people)/12= 40 [given].
Thus, Sum of age of 12 people= 480 years.
Let 'x' be the age of the new person.
(Sum of age of 12 people + x)/13 = 41 [given, average increases by 1].
Sum of age of 12 people + x = 533.
480 + x= 533.
x= 53.
Answer : 53 years.
(Sum of age of 12 people)/12= 40 [given].
Thus, Sum of age of 12 people= 480 years.
Let 'x' be the age of the new person.
(Sum of age of 12 people + x)/13 = 41 [given, average increases by 1].
Sum of age of 12 people + x = 533.
480 + x= 533.
x= 53.
VIRAT said:
1 decade ago
@Sweta weight of 8 persons is increasing when a new person is coming by replacing a person whose weight is given 65 kg,
Now to know the weight of new person we have add the increased weight in 65 kg simple.
8*2.5 = 20 kgs.
So now the weight of new person is 65+20 kg = 85kg.
Now to know the weight of new person we have add the increased weight in 65 kg simple.
8*2.5 = 20 kgs.
So now the weight of new person is 65+20 kg = 85kg.
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