## How do you work out the modal class interval?

You can understand the meaning of modal class interval by examining the meaning of each term in the phrase. **Modal** means the one that occurs most often (averages: mode). In maths, the mode is one of the most common ways to describe a set of data. **A class interval** is the width of one of your groups in the frequency table or, the class interval is what you use when grouping data together. The modal class is, therefore, t**he group with the highest frequency.** For example: if you counted the number of pencils in different pencil cases and you decided to group them. You might record how many pencil cases had 1 to 5 pencils in, how many had 6 to 10 pencils in, how many had 11 – 15 pencils, etc, up to whatever number is practical. In this example, your class intervals are:

- 1 – 5 pencils, 2 pencil cases
- 6 – 10 pencils, 4 pencil cases
- 11 – 15 pencils, 6 pencil cases
- 16 – 20 pencils, 1 pencil case.

If you found that there were more pencil cases with 11 – 15 pencils in than any other class interval,** then 11 – 15 is your modal class interval.**