Question

in the sequence of class intervals 10 - 20, 20 - 30, 30 - 40, etc., the class that includes 20 is

Explanation:

Step1: Understand class - interval convention

In exclusive - type class intervals, the upper - limit of a class is not included in that class. So, 20 is not included in the class interval \(10 - 20\).

Step2: Identify the correct class

The next class interval is \(20 - 30\), and according to the convention of exclusive - type class intervals, 20 is included in the class interval \(20 - 30\).

Answer:

\(20 - 30\)