Watts Electronics (Adapted from Heizer Render, Operations Management, 2006.)

Watts Electronics manufactures three products: internal modems, external modems, and graphics circuit boards. Production of each product requires testing on each of three test devices. The following table shows the minutes required to test each product on each device. For example, producing each internal modem requires 7 minutes of testing on test device 1, 2 minutes on test device 2, and 5 minutes on test device 3.

	Test Device #1	Test Device #2	Test Device #3
Internal Modems	7	2	5
External Modems	3	5	2
Graphics Boards	8	3	3

Test devices 1 and 2 are each available for 120 hours per week. Test device 3 requires additional preventative maintenance and is available for 100 hours per week. Each test device requires an operating technician. The cost for a technician is $15 per hour. In addition, each device uses various disposable supplies while it is being operated. The cost of disposable supplies for test device 1 is $5 per hour. The corresponding costs for test devices 2 and 3 are $2 and $8 per hour respectively.

The following table shows the expected revenue and material cost per unit for each of the six products. Watts Electronics wishes to maximize profits. The market for each product is large enough that Watts believes it can sell any products made.

Product	Revenue per Unit Sold ($)	Material Cost per Unit ($)
Internal Modems	200	35
External Modems	150	25
Graphics Boards	210	40

Watts Electronics wishes to maximize profits. Write an LP in Excel (decision variables, objective function and constraints) and solve by solver.

	Revenue	Material Cost
Internal Modem	$ 200	$ 35
External Modem	$ 150	$ 25
Graphics Boards	$ 210	$ 40
Minutes Required	Test Device 1	Test Device 2	Test Device 3
Internal Modem	7	2	5
External Modem	3	5	2
Graphics Boards	8	3	3
Hours / Week	120	120	100
Test Device Operating Costs
Labor Cost / Hour	$ 15	$ 15	$ 15
Material Cost / Hour	$ 5	$ 2	$ 8