chapter  6
4 Pages

Averages (Arithmetic Mean) and Median

The operator of a waterworks or wastewater treatment plant takes a chlorine residual measurement every day and part of the operating log is shown in Table 6.1. Find the mean.

Solution

Add up the seven chlorine residual readings: 0.9 + 1.0 + 0.9 + 1.3 + 1.1 + 1.4 + 1.2 = 7.8. Next, divide by the number of measurements (in this case, seven): 7.8

7 = 1.11. The mean chlorine residual for the week was 1.11 mg/L.