Context: You are a safety inspector for public swimming pools. The CDC recommends a chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs/spas. You gather a sample of chlorine concentrations from public swimming pools in the area and obtain the following data. For your convenience, the data has been sorted.
c) The interquartile range (IQR) (literally stands for "the range between the quartiles") represents the spread of the middle-half of the data (rather than the range, which is the total spread of the data). The name gives away how to calculate it. Since it is the "range between the quartiles", just subtract Q3 and Q1 to find the IQR.
IQR:
d) Summary sentence: The chlorine concentrations, based on this sample, are centered about a median of ppm (representing a typical pool), and the middle-half of chlorine concentrations are spread over an IQR of ppm.
