The following data on y = glucose concentration (g/L) and x = fermentation time (days) f...

The following data on y = glucose concentration (g/L) and x = fermentation time (days) for a particular blend of malt liquor was read from a scatter plot in the article “Improving Fermentation Productivity with Reverse Osmosis” (Food Tech., 1984: 92–96):

a. Verify that a scatter plot of the data is consistent with the choice of a quadratic regression model.

b. The estimated quadratic regression equation is . Predict the value of glucose concentration for a fermentation time of 6 days, and compute the corresponding residual.

c. Using SSE = 61.77, what proportion of observed variation can be attributed to the quadratic regression relationship?

d. The n = 8standardized residuals based on the quadratic model are 1.91, –1.95, –.25, .58, .90, .04, –.66, and .20. Construct a plot of the standardized residuals versus x and a normal probability plot. Do the plots exhibit any troublesome features?

e. The estimated standard deviation of —that is, Compute

f. Compute a 95% PI for a glucose concentration observation made after 6 days of fermentation time.