A company has been tracking sales (in thousands) of a new product by month along with their monthly marketing spend (in thousands) on the new product.They have also been recording the average daily number of Tweets about the product in that month and the average daily number of Facebook likes for the product in that month.

A linear regression has been performed to predict sales in the future months. The equation is as follows:

Sales = 166.2662 + 2.26*Marketing + -4.397*Tweets + .248*Facebook

a. Are all three independent variables needed to predict sales? Explain.

b. What does it mean that tweets has a negative coefficient before it? Are they helping or hurting their sales, explain how you know.

c. What are the expected monthly sales if they spend $145,000 on marketing, get an average of 73 Tweets, and get an average of 189 Facebook likes?

d. What is the expected increase in sales with each additional $10,000 spent on marketing?