Choose the correct answer in each of the following questions:
In the class intervals 10-20, 20-30, the number 20 is included in
(a) 10-20
(b) 20-30
(c) in each of 10-20 and 20-30
(d) in none of 10-20 and 20-30

ANSWER:
(b) 20 − 30
This is the continuous form of frequency distribution. Here, the upper limit of each class is excluded, while the
lower limit is included. So, the number 20 is included in the class interval 20 − 30.