help me understand

Here is a data set: 60500 51300 50600 63600 53500 51900 47200 54600 57500 57000 52700 54900 59300 55500 53100 51800 58600 55400 50800 55200 58900 58000 61000 65800 50500 56700 55000 54200 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 and the first lower class limit should be. What is the best class width for this data set? optimal class width = What should be the first lower class limit? 1st lower class limit =