Class Interval Size for Marks Data

For the marks data of 100 students (range 0–100), if we choose 10 equal class intervals, what is the class interval size?

Correct Answer Explanation

Class Interval = Range / Number of Classes = 100 / 10 = 10.

Key Calculation:

• Range = 100 − 0 = 100
• Number of classes = 10
• Class interval = 100 / 10 = 10
• Classes: 0–10, 10–20, 20–30, ..., 90–100

Interlinked Decisions:

If we choose class interval = 10, then number of classes = 100/10 = 10. If we choose interval = 20, classes = 100/20 = 5. These two decisions are always linked.