Business Statistics

Chapter 2 | Charts and Graphs 17

2.2.1 Class Midpoint

The class midpoint is the value halfway between

the lower and the upper class limits. It can be cal-

culated as the average of the class endpoints. From

Table 2.3, the midpoint for the rst class interval

is = (72 + 75)/2 = 73.5 (average of class endpoints

72 and 75). The calculation of the class midpoint

is important because it is the representative value

in each class for most statistical calculations.

Table 2.4 exhibits the frequency distribution of

sales of a pharmaceutical company with class

midpoint.

2.2.2  Relative Frequency

To compare the distribution of frequencies in two ...