Mark Price, the new productions manager for Speakers and Company, needs to find out which variable most affects the demand for their line of computer speakers. He is uncertain whether the unit price of the product or the effects of increased marketing are the main drivers in sales and wants to use regression analysis to figure out which factor drives more demand for its particular market. Pertinent information was collected by an extensive marketing project that lasted over the past 12 years and was reduced to the data that follow:

YEAR	UNIT SALES (THOUSANDS)	PRICE $ PER UNIT	ADVERTISING ($000)
1	400	280	600
2	700	215	835
3	900	211	1,100
4	1,300	210	1,400
5	1,150	215	1,200
6	1,200	200	1,300
7	900	225	900
8	1,100	207	1,100
9	980	220	700
10	1,234	211	900
11	925	227	700
12	800	245	690

a. Perform a regression analysis based on these data using Excel.

Note: Negative values should be indicated by a minus sign. Round your answers to 4 decimal places.

c. Predict average yearly speaker sales for Speakers and Company based on the regression results if the price was $300 per unit and the amount spent on advertising (in thousands) was $900.

Note: Enter your answer in thousands. Do not round intermediate calculations. Round your answer to 2 decimal places.