Daily air quality is measured by the air quality index (AQI) reported by the Environmental Protection Agency. This index reports the pollution level and what associated health effects might be a concern. The index is calculated for five major air pollutants regulated by the Clean Air Act. and takes values from 0 to 300, where a higher value indicates lower air quality. AQI was reported for a sample of 91 days in 2011 in Durham, NC. The relative frequency histogram below shows the distribution of the AQI values on these days. Required:
a. Describe the distribution.
b. Estimate the median AQI.
c. Would you expect the mean to be higher or lower than the median? Explain.
d. Estimate the IQR of the AQI.