109. In bio ltration of wastewater, air discharged from a treatment facility is passed through a damp Removal Removal Obs Temp % Obs Temp %
1 7.68 98.09 17 8.55 98.27 2 6.51 98.25 18 7.57 98.00 3 6.43 97.82 19 6.94 98.09 4 5.48 97.82 20 8.32 98.25 5 6.57 97.82 21 10.50 98.41 6 10.22 97.93 22 16.02 98.51 7 15.69 98.38 23 17.83 98.71 8 16.77 98.89 24 17.03 98.79 9 17.13 98.96 25 16.18 98.87 10 17.63 98.90 26 16.26 98.76 11 16.72 98.68 27 14.44 98.58 12 15.45 98.69 28 12.78 98.73 13 12.06 98.51 29 12.25 98.45 14 11.44 98.09 30 11.69 98.37 15 10.17 98.25 31 11.34 98.36 16 9.64 98.36 32 10.97 98.45 porous membrane that causes contaminants to dissolve in water and be transformed into harmless products. The accompanying data on x  inlet temperature (C) and y  removal ef ciency (%)
was the basis for a scatter plot that appeared in the article Treatment of Mixed Hydrogen Sul de and Organic Vapors in a Rock Medium Bio lter (Water Environ. Res., 2001: 426—435).
Calculated summary quantities are xi 
384.26, yi3149.04, , xiyi  37,850.7762,and .

a. Does a scatter plot of the data suggest appropriateness of the simple linear regression model?

b. Fit the simple linear regression model, obtain a point prediction of removal ef ciency when temperature  10.50, and calculate the value of the corresponding residual.

c. Roughly what is the size of a typical deviation of points in the scatter plot from the least squares line?

d. What proportion of observed variation in removal ef ciency can be attributed to the model relationship?

e. Estimate the slope coef cient in a way that conveys information about reliability and precision, and interpret your estimate.

f. Personal communication with the authors of the article revealed that one additional observation was not included in their scatter plot: (6.53, 96.55). What impact does this additional observation have on the equation of the least squares line and the values of s and r2?