Attempting to analyze the relationship between advertising and sales, the owner of a furniture store ...

Attempting to analyze the relationship between advertising and sales, the owner of a furniture store recorded the monthly advertising budget ($ thousands) and the sales ($ millions) for a sample of 12 months. The data are listed here. 

Advertising  23   46    60    54   28   33

Sales        9.6  11.3  12.8  9.8   8.9  12.5

Advertising   25     31     36     88     90     99

Sales          12.0  11.4  12.6  13.7  14.4  15.9

a) Draw a scatter diagram. Does it appear that advertising and sales are linearly related?

b) Calculate the least squares line and interpret the coefficients.