(b) The data in the table below are the results of a study to determine the recovery of a large dead zone in a lake in Colorado after the Clean Water Act was enacted. Data were collected daily over the months of June, July, and August in the years listed. Average values for the three months in the years where water quality assessment was performed are given in the table. Water Quality Assessment for Colorado Lake

Year Temperature (°C) Dissolved Oxygen (DO)(mg/L) Alkalinity (CaCO3mg/L) pH Tot. Phosphorus (mg/L) Turbidity (depth in m)
1965 20.1 3.3 274 8.1 3.35 N/A
1975 17.3 8.6 181 8.8 1.14 1.2
2008 16.9 9.4 155 8.8 0.652 1.7
2014 17.8 8.6 124 8.4 0.282 2.0
i. Calculate the percent change in average daily temperature in June, July, and August between 1965 and 1975.
ii. Calculate the average change of dissolved oxygen per year in the lake over the course of the study. Show your work.
iii. Calculate how many times greater the change in phosphorous levels between 1965 and 1975 is than between 2008 and 2014. Show your work.