Air pollution can be measured using the units average particulate pollution (PM2.5). Air pollution levels over 10 PM2.5 are considered hazardous to health by the World Health Organization (WHO). The names and the levels of pollution (in PM2.5) for the five worst U.S. cities are shown in Table 32.
Table 32
Air Pollution for the Five Worst U.S. Cities
City Air Pollution (PM2.5)
Bakersfield, CA ………………… 18.2
Merced, CA ……………………. 18.2
Fresno, CA ………………… ….. 17.0
Hanford, CA …………………… 16.2
Los Angeles, CA ………………… 15.3
Let n be the number of cities listed in Table 32, and let xi be the air pollution (in PM2.5) of the city listed in the ith row of the table.
a. Find the values of x1, x2, x3, x4, and x5.
b. Find Σxi. What does it mean in this situation?
c. Find Σxi/n. What does it mean in this situation?