An electronics company is looking to develop a regression model to predict the number of units sold for a special running watch.

Sales (units)	Price ($)	Advertising ($)
500	100	50
480	120	40
485	110	45
510	103	55
490	108	40
488	109	30
496	106	45

a. Should this company use both price and promotion dollars, or just one of them only, to determine the sales? Perform data analysis and explain.
b. Use the model you determined (multiple regression) to predict sales if price is set at $125 and advertising is $55.
c. Then compare the forecast in (b) above with the forecast you would have made using each independent variable separately (alone).