The average marks of four subjects is 120. If 33 was misread as 13 during the calculation, what will be the correct average?
A. 122
B. 120
C. 125
D. 121
Answer: Option C
Solution (By Examveda Team)
$$\eqalign{ & {\text{Correct average}} \cr & = 120 + \left( {\frac{{33 - 13}}{4}} \right) \cr & = 120 + 5 \cr & = 125 \cr} $$Solve while reading method:
Average given is 120.
Difference of 33 and 13 is 20.
That means 20 must be added to total.
Then average of is and so must be added to average, i.e.
Correct average = 120 + 5 = 125
This Question Belongs to Arithmetic Ability >> Average
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The average of the four subjects is 120. This means the total marks for all four subjects are:
Total marks
=
120
×
4
=
480
Total marks=120×4=480
During the calculation, the value 33 was misread as 13. So, the total marks were calculated with a value of 13 instead of 33. To correct this, we need to replace the incorrect 13 with the correct value of 33.
The difference between the correct value (33) and the misread value (13) is:
Difference
=
33
−
13
=
20
Difference=33−13=20
To correct the total marks, we add this difference (20) to the miscalculated total:
Correct total marks
=
480
+
20
=
500
Correct total marks=480+20=500
Now, to find the correct average, divide the correct total marks by the number of subjects (4):
Correct average
=
500
4
=
125
Correct average=
4
500
=125
Thus, the correct average is 125.
120- 20/4=115 is correct average
115
Total 120*4 = 480
480+33-13=500
Correct average = 500/4= 125 (Ans)
Sum of 4 subjects is 4×120=480
33 is misread as 13
The difference between 33-13=20
New sum of 4 subjects is 480+20=50p
Average of new 4 subjects is 500/4=125
average of misread = (33-13)/4 = 5
Correct average = 120 + 5 = 125
120*4=480 , 480-13+33=500 500/4=122.22
Shouldn't we solve it according to above mentioned method?