Thayer Corporation is a mayor defense contractor, producing artillery shells for the Marine Corps landing craft. A recent study of production over past year shows the following relationship between labor inputs and output (production function): Labor (Persons) Output (Shells) 10 2700 20 3000 30 3280 40 3530 50 3750 60 3950 70 4130 80 4280 90 4400 100 4500 Marine Corps has agreed to buy shells (any number) at a price of $ 20.00 per shell. Marginal cost of labor is $380. 1. Calculate the exact optimal level of labor to be used. Hint: Use the linear interpolation method discussed in class. Show calculations.