Your seasonally adjusted monthly sales forecast is $382,190 +$4,011 (Month number), where the month number is 1 for Jan. 2011 and increases by 1 each month. The seasonal index for February sales is 0.923, and it is 1.137 for April. What you need now is a forecast for cost of goods sold in order to plan ahead for filling future orders. You have found that monthly sales have been a good predictor of monthly cost of goods sold and have estimated the following regression equation: Predicted cost of good sold = $106,582 + 0:413 (Sales) 

a. Find the seasonally adjusted forecast of monthly sales for Feb. 2018. 

b. Find the forecast of monthly sales for Feb. 2018. 

c. Find the forecast of cost of goods sold for Feb. 2018. 

d. Find the forecast of cost of goods sold for Apr. 2019.