Question

the fourth class interval for a grouped data whose first and second class intervals are 10 - 15 and 15 - 20 respectively is

Explanation:

Step1: Identify class - width

The class - width is found by subtracting the lower limit of the second class from the lower limit of the first class. For the classes \(10 - 15\) and \(15 - 20\), the class - width \(w=15 - 10=5\).

Step2: Find the third class interval

The third class interval will start where the second class interval ends. Since the second class interval is \(15 - 20\), the third class interval is \(20 - 25\) (because the lower limit of the third class is the upper limit of the second class and the class - width is 5).

Step3: Find the fourth class interval

The fourth class interval will start where the third class interval ends. Since the third class interval is \(20 - 25\), the fourth class interval is \(25 - 30\).

Answer:

\(25 - 30\)