Guidelines for Frequency Distributions
(As stated in your textbook (R.A. Donnelly Jr., Ph.D.)

1. The classes should all be of equal size.

2. The classes need to be mutually exclusive...

3. Try to have no fewer than 5 classes and no more than 15 classes.

4. Avoid open-ended classes, if possible.

5. All data values from the original table need to be included in a class.