Aptitude - Average - Discussion
Discussion Forum : Average - General Questions (Q.No. 15)
15.
A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half (1/2). The number of pupils in the class is:
Answer: Option
Explanation:
Let there be x pupils in the class.
| Total increase in marks = |  |
x x | 1 |  |
= | x |
| 2 | 2 |
 |
x | = (83 - 63)  |
x | = 20 x= 40. |
| 2 | 2 |
Discussion:
123 comments Page 8 of 13.
Ravi said:
1 decade ago
Let total of other students be x and number of students be n,
(x+83)/n - (x+63)/n = 1/2.
(x+83-x-63)/n = 1/2.
20/n = 1/2.
Therefore n = 40.
(x+83)/n - (x+63)/n = 1/2.
(x+83-x-63)/n = 1/2.
20/n = 1/2.
Therefore n = 40.
Mohit Tomar said:
9 years ago
Let as take, m is actual total marks of students and p is number of the pupil.
Difference between average = 1/2.
m/p - (m+20)/p = 1/2.
p = 40.
Difference between average = 1/2.
m/p - (m+20)/p = 1/2.
p = 40.
Ajay said:
1 decade ago
Ans of Savinder question
Let total no of cand-x
Dec in aver- 50-45=5
Total dec in numbers= 5x
then, 5x= 100(90-60)
x=600 ( Ans)
Let total no of cand-x
Dec in aver- 50-45=5
Total dec in numbers= 5x
then, 5x= 100(90-60)
x=600 ( Ans)
(1)
Tukaram D. Yedale said:
1 decade ago
Hi guys !
Let no.of people = x (83/x) - (63/x) = 1/2 after solving this we get x= 40 it is very easy method to understand is't it ?
Let no.of people = x (83/x) - (63/x) = 1/2 after solving this we get x= 40 it is very easy method to understand is't it ?
Utsav Sinha said:
8 years ago
Simple logic.
Let no.of candidate = x.
Their average marks =y.
Generate an equation,
xy+83-63=x(y+1/2).
Solving we get y=40.
Let no.of candidate = x.
Their average marks =y.
Generate an equation,
xy+83-63=x(y+1/2).
Solving we get y=40.
Shubham said:
3 years ago
Here, the Question says A Pupil's which refers to only one student.
While pupils stand for multiple students.
Am I right?
While pupils stand for multiple students.
Am I right?
(7)
Abhishek said:
8 years ago
@Utsav Sinha.
RHS should be;
X (y + 1/2y). Because average is increasing by half that means avg + 1/2 of avg.
RHS should be;
X (y + 1/2y). Because average is increasing by half that means avg + 1/2 of avg.
Karthy said:
1 decade ago
The average increase for one person is 0.5
Total increase is 20
Therefore Total no of pupil =20/0.5 = 40.
Total increase is 20
Therefore Total no of pupil =20/0.5 = 40.
(2)
Chinmay said:
8 years ago
Total marks=x,
Number of pupils=y,
Average=x/y.
But,
(x+y)/20=x/y+1/2,
(x+20)/y=(2x+y)/2y,
Therefore y=40.
Number of pupils=y,
Average=x/y.
But,
(x+y)/20=x/y+1/2,
(x+20)/y=(2x+y)/2y,
Therefore y=40.
Deepak kumar said:
8 years ago
Let x is average marks when total marks are 63.
Replacement,
83 - 63 = 20.
Then, x + 20 = x\2.
X = 40.
Replacement,
83 - 63 = 20.
Then, x + 20 = x\2.
X = 40.
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