The maintenance of swimming pools is costly because of all the chlorine that is needed to keep
Question:
The maintenance of swimming pools is costly because of all the chlorine that is needed to keep the water clear and free of germs. A chain of hotels with outdoor pools seeking to reduce casts decided to analyze the factors that determine how much chlorine is needed. The chain hired a chemist to do the analysis. It is believed that the speed at which chlorine in the pool is depleted depends on the temperature of the water (higher temperature uses chlorine faster); pH level, which is a measure of the acidity of the water (pH ranges from 0) to 14, with 0 being very acidic and 14 being very alkaline; levels around 7.5 use the least chlorine); and weather (sunshine uses up chlorine). The chemist conducted the following experiment. The percentage of chlorine depletion during 8-hour days was recorded under varying conditions of pH level, water temperature, and weather conditions. The data were recorded in the following way:
(a) Estimate the following model Pct. Dep = b 0 + b 1 Temperature + b 2 PH. Level. Write down the regression equation.
(b) Plot PH. level against the dependent variable Pet . dep.
(c) How would you modify the original regression to incorporate the information in part (lb)?
(d) Test if dummy variables and the additional regressor(s) from part (1c) should be added to the original regression model? Use a = 0.05.
(e) Test to determine if the model in part (1d) is valid.
(f) Can we infer that higher temperatures deplete chlorine more quickly?
(g) Is there evidence to infer that the belief about the relationship between chlorine depletion and pH level is correct?
(h) Can we infer that weather is a factor in chlorine depletion?
Expert Answer:
a The following table is from the excel output Coefficients Standard Error t Stat Pvalue Intercept 9780238095 696568411 1404059952 0161799543 Temperat... View the full answer
