Question

If a frequency distribution of Data Set C is constructed with 10 classes with the lowest average at $20 and the highest average at $60, what should the class width be?
Data Set C: Dollar Averages per Customer in a Photography Studio

22, 23, 25, 25, 26, 27, 28, 28, 33, 33, 34, 36, 36, 38, 39, 41, 41, 42, 45, 53, 54

A ) 4
B ) 2
C ) None of these
D ) 6
E ) 7