12.20 The following model was fitted to a sample of 30 families in order to explain household milk consumption:

y = b0 + b1x1 + b2x2 + e where y = milk consumption, in quarts per week x1 = weekly income, in hundreds of dollars x2 = family size The least squares estimates of the regression parameters were as follows:

b0 = -0.025 b1 = 0.052 b2 = 1.14 The total sum of squares and regression sum of squares were found to be as follows:

SST = 162.1 and SSR = 88.2

a. Compute and interpret the coefficient of determination.

b. Compute the adjusted coefficient of determination.

c. Compute and interpret the coefficient of multiple correlation.