The attached Data set is from Big Andy's Burger Barn hamburger chain.

You believe that the monthly sales should be affected by price and the monthly advertising cost.

The data provided include three columns:

SALES- monthly sales revenue in a given city (in $1000)

PRICE- a price index in that city (in $)

ADVERT- monthly advertising expenditure in that city (in $1000).

(a) Please write the regression model you would like to use. Note: Please also include the error term.

(b) Run a regression based on your model.

(c) Interpret the coefficients of your independent variables.

sales price advert 73.2 5.69 1.3 71.8 6.49 2.9 62.4 5.63 0.8 67.4 6.22 0.7 89.3 5.02 1.5 70.3 6.41 1.3 73.2 5.85 1.8 86.1 5.41 2.4 81 6.24 0.7 76.4 6.2 3 76.6 5.48 2.8 82.2 6.14 2.7 82.1 5.37 2.8 68.6 6.45 2.8 76.5 5.35 2.3 80.3 5.22 1.7 70.7 5.89 1.5 75 5.21 0.8 73.7 6 2.9 71.2 6.37 0.5 84.7 5.33 2.1 73.6 5.23 0.8 73.7 5.88 1.1 78.1 6.24 1.9 75.7 5.59 2.1 74.4 6.22 1.3 68.7 6.41 1.1 83.9 4.96 1.1 86.1 4.83 2.9 73.7 6.35 1.4 75.7 6.47 2.5 78.8 5.69 3 73.7 5.56 1 80.2 6.41 3.1 69.9 5.54 0.5 69.1 6.47 2.7 83.8 4.94 0.9 84.3 6.16 1.5 66 5.93 2.8 84.3 5.2 2.3 79.5 5.62 1.2 80.2 5.28 3.167.6 5.46 1 86.5 5.11 2.5 87.6 5.04 2.1 84.2 5.08 2.8 75.2 5.86 3.1 84.7 4.89 3.1 73.7 5.68 0.9 81.2 5.83 1.8 69 6.33 3.1 69.7 6.47 1.9 78.1 5.7 0.7 88 5.22 1.6 80.4 5.05 2.9 79.7 5.76 2.3 73.2 6.25 1.7 85.9 5.34 1.8 83.3 4.98 0.6 73.6 6.39 3.1 79.2 6.22 1.2 88.1 5.1 2.1 64.5 6.49 0.5 84.1 4.86 2.9 91.2 5.1 1.6 71.8 5.98 1.5 80.6 5.02 2 73.1 5.08 1.3 81 5.23 1.1 73.7 6.02 2.2 82.2 5.73 1.7 74.2 5.11 0.7 75.4 5.71 0.7 81.3 5.45 2 75 6.05 2.2