Question

In an examination, the mean of marks scored by a class of 40 students was calculated as 72.5 Later on it was detected that the marks of one student were wrongly copied as 48 instead of 84. Find the correct mean​

Answer 1

Answer:

Mean of marks =18.2

Number of students =40

Total marks of 40 students =40×18.2=728

Difference of marks when copied wrongly =29−21=8

So total marks =728+8=736

∴mean =736/40

=18.4

Hence the correct mean is 18.4.