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In an examination, the mean of marks sc...

In an examination, the mean of marks scored by a class of 30 students was calculated as 58.5 Later on, it was detected that the marks of one student was wrongly copied as 57 instead of 75. Find the correct mean.

A

`60.1`

B

`58`

C

`59`

D

`59.1`

Text Solution

Verified by Experts

The correct Answer is:
D
`"Mean of marks" = ("incorrect marks of 30 students")/(30)`
`therefore" "58.5 = ("incorrect sum of marks")/(30)`
` rArr " ""Incorrect sum of marks" = 58.5 xx 30 = 1755`
As marks of one student was wrongly copied as 57 instead of 75, correct sum of marks
`="Wrong sum - Wrong value + Correct value"`
`=1755 - 57 + 75 = 1773`
`therefore" ""Correct mean " = (1773)/(30) = 59.1`
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