The data shows the hypothetical quantity demanded (Y) of a commodity, its price (X1), and consumers' income (X2). ...

        Demand (units) Price ($) per unit Income (in $00s)    40 9 400    45 8 500    50 9 600    55 8 700    60 7 800    70 6 900    65 6 1000    65 8 1100    75 5 1200    75 5 1300    80 5 1400    100 3 1500    90 4 1600    95 3 1700    85 4 1800          The data   shows the hypothetical quantity demanded (Y) of a commodity, its price (X1),   and consumers' income (X2). The data is given in the "Data"   worksheet.         (a) Use   Excel's regression feature to create a model to predict the demand based on   price.   (b) Use   Excel's regression feature to create a model to predict the demand based on   income.   (c) Write   the linear equations for both the models.    (d) Are   these models useful in predicting the demand of the commodity? Explain.   (e) Which of   these two models is better? Explain.    (f) Use   Excel's regression feature to create a multiple-regression model using both   price and income.   (g) Write   the prediction equation for this model from (f).   (h) Is this   model useful in predicting the demand of the commodity? Explain.   (i) How does   this model compare with the two models from (a) and (b)? Explain.