Question

If in a class of 20students ,5students,have scored76 marks 7 students have scored 77 marks and 8 students have scored 78 marks then compute the mean of the c lass

Answer 1

Observations are 76,76,76,76,76,77,77,77,77,77,77,77,78,78,78,78,78,78,78,78.

Hence, Mean = {5(76) + 7(77) + 8(78)}/20

                      = 1543/20 = 77.15

Answer 2

As per given data:

The total marks obtained by 5 students=5×76=380

The total marks obtained by 7 students=7×77=536

The total marks obtained by 8 students =8×78=624

Then total marks obtained by 20 students=380+536+624=1543

Mean= sum of observations/no.of observations

Mean of the class=1543/20=77.15