Class Boundaries are the midpoints between the upper-class limit of a class and the lower class limit of the next class in the sequence.

Therefore, each class has an upper and lower class boundary.

Example:

Class             Frequency

200-299           10

300-399           12

For the first class, 200-299

The lower-class boundary is the midpoint between 199 and 299 that is 199.5

The upper-class boundary is the midpoint between 299 and 300 that is 299.5