Aptitude - Average - Discussion
Discussion Forum : Average - General Questions (Q.No. 11)
11.
The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is:
Answer: Option
Explanation:
Let A, B, C represent their respective weights. Then, we have:
A + B + C = (45 x 3) = 135 .... (i)
A + B = (40 x 2) = 80 .... (ii)
B + C = (43 x 2) = 86 ....(iii)
Adding (ii) and (iii), we get: A + 2B + C = 166 .... (iv)
Subtracting (i) from (iv), we get : B = 31.
B's weight = 31 kg.
Discussion:
40 comments Page 2 of 4.
Raj tiwari said:
8 years ago
Very easy and best trick, understand the average as equal distribution of data.
As average of A,B,C = 45.
means all is 45.
a+b is 40 , but as both should be 45, means someone took 5 from both to make them 40.
means 10 is taken so keep value -10 in mind.
Similarly for a+c = 43 , 2 is less so someone taken 2 from.both means -4 is been taken from both.
So.from both case 10 and 4.
-14 is been taken.
.
And as b is the question lets make b as the robbery and if the average should be 45 and as b taken 14 from them.
means b is 45-14 = 31.
As average of A,B,C = 45.
means all is 45.
a+b is 40 , but as both should be 45, means someone took 5 from both to make them 40.
means 10 is taken so keep value -10 in mind.
Similarly for a+c = 43 , 2 is less so someone taken 2 from.both means -4 is been taken from both.
So.from both case 10 and 4.
-14 is been taken.
.
And as b is the question lets make b as the robbery and if the average should be 45 and as b taken 14 from them.
means b is 45-14 = 31.
(7)
Ganeshgore said:
8 years ago
Thanks @Kaustubh.
(1)
Drukyul said:
8 years ago
A+B+C=135.......(1)
B+C=86..............(2)
A+B=80..............(3)
A+86=135.
A=49....................(4)
Sub equ 4 in 3.
49+B=80,
B=80-49,
B=31.
B+C=86..............(2)
A+B=80..............(3)
A+86=135.
A=49....................(4)
Sub equ 4 in 3.
49+B=80,
B=80-49,
B=31.
(2)
THORAT SANDIP said:
8 years ago
A+B+C=135......(1)
B+C=86.....(2)
SUBTRACT EQ. 2 FROM 1, WE GET.
(A+B+C)-(B+C)=135-86=49.
A=49.
A+B=80.....(3).
PUT THE VALUE OF A IN ABOVE EQUATION.
49+B=80,
B=80-49=31.
B+C=86.....(2)
SUBTRACT EQ. 2 FROM 1, WE GET.
(A+B+C)-(B+C)=135-86=49.
A=49.
A+B=80.....(3).
PUT THE VALUE OF A IN ABOVE EQUATION.
49+B=80,
B=80-49=31.
Medha said:
8 years ago
B + c = 86 ( 1)
A + B + C = 135 (2)
A + B = 80 (3)
Substituting (1) in (2)
A = 135 - 86 = 49.
From (3):
B = 80 - 49 = 31.
A + B + C = 135 (2)
A + B = 80 (3)
Substituting (1) in (2)
A = 135 - 86 = 49.
From (3):
B = 80 - 49 = 31.
Anjum said:
8 years ago
Thanks everyone for helping it by giving the explanation.
Ayisha said:
9 years ago
Exactly right. Thank you all.
Anjum said:
9 years ago
Thanks, it is easy to access the answers.
Faisal said:
9 years ago
Thanks @Priyanka.
Sara said:
9 years ago
Thanks, @Krishna. Your explanation was useful.
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