5. A firms sales for a product line during the 12 quarters of the past three years were as follows:

Quarter 1 2 3 4 5 6 7 8 9 10 11 12

Sale 600 1550 1500 1500 2400 3100 2600 2900 3800 4500 4000 4900

The firm uses linear regression to forecast its sales, the results of regression analysis of historical sales data is given below.

You are required to forecast each quarter of the fourth yearthat is, quarters 13, 14, 15, and 16. ???????????/????/