When quantities are measured, their data can be grouped into several classes. The range of each class is called the class interval.
For a class interval of 70 - 79, the lower limit is 70 and the upper limit is 79.
For a class interval of 80 - 89, the lower limit is 80 and the upper limit is 89.
The lower boundary of each class refers to the middle value between the lower limit of the class and the upper limit of the previous class.
The upper boundary of each class refers to the middle value between the upper limit of the class and the lower limit of the following class.
The size of a class interval is the difference between the upper boundary and the lower boundary of the class.
For a class interval of 70 - 79, the lower limit is 70 and the upper limit is 79.
For a class interval of 80 - 89, the lower limit is 80 and the upper limit is 89.
The lower boundary of each class refers to the middle value between the lower limit of the class and the upper limit of the previous class.
The upper boundary of each class refers to the middle value between the upper limit of the class and the lower limit of the following class.
The size of a class interval is the difference between the upper boundary and the lower boundary of the class.
