An article in the Tappi Journal (March, 1986) presented data on green liquor Na 2 S concentration (in grams per liter) and paper machine production (in tons per day). The data (read from a graph) are...

An article in the
Tappi Journal
(March, 1986) presented data on green liquor Na₂S concentration (in grams per liter) and paper machine production (in tons per day). The data (read from a graph) are shown as follows:

(a) Fit a simple linear regression model with
y
= green liquor Na₂S concentration and
x
= production. Find an estimate of σ². Draw a scatter diagram of the data and the resulting least squares fitted model.

(b) Find the fitted value of
y
corresponding to
x
= 910 and the associated residual.

(c) Find the mean green liquor Na₂S concentration when the production rate is 950 tons per day.