To keep cool in the summer months, you decide to design and build your own hand-held fan. The fan's electrical circuit will run off of 4 AA batteries (each with a voltage of 1.5 V) and must not exceed 0.050 A of current. You visit your local Radio Shack and find that resistors are sold in five varieties: 5 Ohm, 10 Ohm, 12 Ohm, 20 Ohm, 50 Ohm. Each resistor costs 8 cents. What set of resistors should you buy to minimize cost?