Dunkirk Consulting wishes to predict the amount of overhead expense that will be incurred by a consulting contract, to develop more accurate bids for future con- tracts. Dunkirk has the following data on 11 completed contracts, detailing how long the project took to complete and what the exact overhead expense was:

a. Using linear regression, develop a regression formula for predicting overhead expense, based on the duration of the project.

b. What is the R of this linear regression model? What does that mean?

c. What does linear regression suggest about the overhead expense of a future project that is expected to be 110 days long?

d. A manager at Dunkirk Consulting feels that the overhead expenses of supply chain consulting projects are generally different from the overhead expenses of marketing consulting projects, because supply chain projects generally require more travel, while marketing projects generally require more spending on exter- nal media services. (In the table above, codes for supply chain projects begin with an "A" while marketing projects begin with a "B.") Considering this obser- vation by the manager, develop a better way to use linear regression to forecast overhead expense. Using this method, how much overhead expense would be predicted for a 110-day project if it were a supply chain project? How much over- head expense for a 110-day marketing project?