The class marks of a frequency distribution are 88, 99, 110, 121, 132, 143. Find the class size.
If the class Mark in a frequency distribution are 19.5,26.5,33.5,40.5,47.5,54.5,61.5, then the class size of distribution is
If the class-marks of a frequency distribution are 10.5, 16.5, 22.5, 28.5, 34.5, then the class-size is