Iowa Is an Agricultural State with a Large Number of Rivers

Essay

Iowa is an agricultural state with a large number of rivers. The use of chemical pesticides and increasing size of livestock herds has created a concern for the water quality in the state. A researcher recently surveyed the rivers of Iowa and analyzed the concentrations of certain chemicals at different locations in the watersheds of Iowa. The cumulative relative frequency plot below displays the distribution of Nitrogen concentrations along the Cedar River. (a)Approximately what percent of the Nitrogen concentration measurements are less than 10 mg/L?
(b)Approximately what percent of the Nitrogen concentration measurements are 12 mg/L or more?
(c)50% of the Nitrogen concentration measurements lie below what approximate value?