9. In a study to determine the relationship between ambient outdoor temperature and the rate of evaporation of water from soil, measurements of average daytime temperature in ◦C and evaporation in mm/day were taken for 40 days. The results are shown in the following table. Temp. Evap. Temp. Evap. Temp. Evap. Temp. Evap. 11.8 2.4 11.8 3.8 18.6 3.5 14.0 1.1 21.5 4.4 24.2 5.0 25.4 5.5 13.6 3.5 16.5 5.0 15.8 2.6 22.1 4.8 25.4 5.1 23.6 4.1 26.8 8.0 25.4 4.8 17.7 2.0 19.1 6.0 24.8 5.4 22.6 3.2 24.7 5.7 21.6 5.9 26.2 4.2 24.4 5.1 24.3 4.7 31.0 4.8 14.2 4.4 15.8 3.3 25.8 5.8 18.9 3.0 14.1 2.2 22.3 4.9 28.3 5.8 24.2 7.1 30.3 5.7 23.2 7.4 29.8 7.8 19.1 1.6 15.2 1.2 19.7 3.3 26.5 5.1

a. Compute the least-squares line for predicting evaporation (y) from temperature (x).

b. Compute 95% confidence intervals for β0 and β1.

c. Predict the evaporation rate when the temperature is 20◦C.

d. Find a 95% confidence interval for the mean evaporation rate for all days with a temperature of 20◦C.

e. Find a 95% prediction interval for the evaporation rate on a given day with a temperature of 20◦C.