Here is a data set:
448387408415
406365418389
426408429425
379375387412
388439372456
401425442365
411383411442


The goal is to construct a grouped frequency distribution table (GFDT) for this data set. The GFDT should have 10 classes with a "nice" class width. Each class should contain its lower class limit, and the lower class limits should all be multiples of the class width.

This problem is to determine what the class width should be.

What is the range of this data set?
range =

Using this information, if the goal is to have 10 classes, what is the nicest class width?
optimal class width =