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The average marks of four subjects is 120. If 33 was misread as 13 during the calculation, what will be the correct average?
Answer & Solution
Correct Answer:
Option
C
$$\eqalign{
& {\text{Correct average}} \cr
& = 120 + \left( {\frac{{33 - 13}}{4}} \right) \cr
& = 120 + 5 \cr
& = 125 \cr} $$
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
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
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LoginTotal 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.
480+33-13=500
Correct average = 500/4= 125 (Ans)
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
Correct average = 120 + 5 = 125
Shouldn't we solve it according to above mentioned method?