Question

What is the class interval and frequency of the 4th group for the following distribution table?

Marks Obtained	Less than 5	Less than 10	Less than 15	Less than 20	Less than 25
No. of Students (Cumulative)	4	6	10	13	17

• A. Class interval: 20- 25 and Frequency: 13.
• B. Class interval: 21- 25 and
  Frequency : 13.
• C. Class interval: 15- 20 and
  Frequency: 3.
• D. Class interval: 15- 19 and
  Frequency: 3.

Answer 1

The correct option is C Class interval: 15- 20 and

Frequency: 3.
Upper limits have been given in the table and difference of the upper limits of different classes is 5.

Class intervals will be 0 - 5, 5 - 10, 10 - 15, 15 - 20, 20 -25.

Less than cumulative frequency distribution is given in the table.

The progressive sum of the frequencies from the first data value to a particular data value is the less than cumulative frequency.

Class intervals	Frequency	Cumulative frequency
0-5	4-0 = 4	4
5-10	6-4 = 2	6
10-15	10-6 = 4	10
15-20	13-10 = 3	13
20-25	17- 13 = 4	17

Hence for the 4th group, class interval is 15 -20 and frequency is 3.