Question

Class Interval	Frequency
1 - 10	12
11 - 20	18
21 - 30	23
31 - 40	15
41 - 50	10

• A.

  Class Interval cumulative	Frequency
  1 - 10	30
  11 - 20	53
  21 - 30	68
  31 - 40	78
  41 - 50	91

• B.

  Class Interval	cumulative frequency
  1 - 10	12
  11 - 20	30
  21 - 30	53
  31 - 40	68
  41 - 50	78

• C. Cannot be determined
• D. None of these

Answer 1

Answer: (B)

Class Interval	cumulative frequency
1 - 10	12
11 - 20	30
21 - 30	53
31 - 40	68
41 - 50	78

A Cumulative frequency distribution is the sum of the class and all classes below it in a frequency distribution.

Therefore, we have

$CI$ $CF$

$1-10$ $12$

$11-20$ $12+18=30$

$21-30$ $30+23=53$

$31-40$ $53+15=68$

$41-50$ $68+10=78$

Hence,option $B$ is correct.