A list of results is called a data set. If there are large amounts of data in a data set, then they are segregated into groups. The width of these groups are called class intervals.
Using the class intervals, a frequency diagram or histogram can be drawn.
Notation for class intervals
Class internals are written in the following form:
When measuring time in seconds for a given class of frequency, in a table the following is written, for example:
If time is seconds is between 85 – 90 seconds – this is written as 85 ≤ t < 90 (this is represented as “time being larger or equal to 85 and less than 90 seconds).
t – represents time