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Aptitude - Average - Discussion

Discussion Forum : Average - General Questions (Q.No. 15)
Average
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:
10
20
40
73
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:
125 comments Page 9 of 13.
Deepak kumar said:   9 years ago
Let x is average marks when total marks are 63.
Replacement,

83 - 63 = 20.
Then, x + 20 = x\2.
X = 40.
Dinesh said:   1 decade ago
Its very simple given difference of avg is half hence,
(83/x)-(63/x) = 0.5.

Hence by solve x = 40.
Pawan yadav said:   7 years ago
Let x = total number of student.
Increase 1/2 means x * 1/2 = x/2,
Means x/2 = 83-63
x = 40.
Rav said:   1 decade ago
In the question above
is "A pupil's" mean "A student" ?
Abhishek Ojha said:   8 years ago
@Shubham.

In your case, You calculated Average Marks Not num of the pupil.
Sahr smk said:   3 months ago
Difference =20.
No of pupils = 20 divided increased number.
= 20/0.5,
= 40.
Mr.Pirate said:   4 years ago
No of pupil = x.
Avg = Total/no. Of pupil.
1/2=(83-63)/x.
0.5=20/x,
X=40.
(46)
Mudit said:   7 years ago
I didn't understand why we are multiplying x with 1/2? Please tell me.
Krishna kanth said:   2 decades ago
I didn't understand anything please please please some body explain.
MGM said:   8 years ago
How about this?

(83- 63)/ ? = 1/2
that is 20/ (1/2) = ?
Ans 40.
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