Question

The marks obtained by 110 students in an examination are given below:

Marks:	30-35	35-40	40-45	45-50	50-55	55-60	60-65
Frequencу:	14	16	28	23	18	8	3

Find the mean marks of the students.

Answer 1

Given: The class marks are 32.5, 37.5, 42.5, 47.5, 52.5, 57.5 and 62.5.

Calculation: \[\sum f_{i}x_{i}=455+600+1190+1092.5+945+460+187.5=4930\] 

Answer: \[\overline{X}=\dfrac{4930}{110}=44.81818\ldots\approx44.82\] marks.