Question

Marks of the 100 students are distributed in the grouped frequency distribution table.

Class marks (Marks)	50	60	70	80	90	100
No. of Students (Frequency)	32	15	21	14	17	9

What is the class interval for the group having frequency 17?

• A. 90 - 100
• B. 95 - 105
• C. 80 - 90
• D. 85 - 95

Answer 1

The correct option is D 85 - 95

As class marks are given, class intervals need to be calculated from the class marks.

Difference between the two successive classes = h = 60 - 50 =10

If x is the class marks then, lower and upper boundary of every class is x - $\frac{h}{2}$ and x + $\frac{h}{2}$.

For the group having frequency 17:

Lower boundary = 90 - $\frac{10}{2}$ = 85.

Upper boundary = 90 + $\frac{10}{2}$ = 95.

The class interval is 85 - 95.