The average marks of 18 students was calculated to be 65.
However, it was later found out that the marks of one student had been wrongly entered as 24 instead of 34 and 88 instead of 78 . Find the correct mean.

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Solution

Average marks of 18 students = 65

then Sum of marks of 18 students = 18 x 65 = 1170

Marks of 1 student wrongly entered as 24 instead of 34 and 88 instead of 78

Hence 24 and 88 should be subtracted and 34 & 78 shouled be added

So, Sum of Correct marks = 1170 -24 + 34 -88 + 78 = 1282 - 112 = 1170

Hence the Correct mean = 1170/18 = 65 Ans.

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The average marks of 18 students was calculated to be 65. However, it was later found out that the marks of one student had been wrongly entered as 24 instead of 34 and 88 instead of 78 . Find the correct mean.

The average marks of 18 students was calculated to be 65.
However, it was later found out that the marks of one student had been wrongly entered as 24 instead of 34 and 88 instead of 78 . Find the correct mean.