As a design engineer, you are asked to design a Lighting system consisting of a 70-W power...

As a design engineer, you are asked to design a Lighting system consisting of a 70-W power supply

And two lightbulbs as shown in Fig. 2.124. You must select the two bulbs from the following three available bulbs.

R1= 80 Ω, cost = $0.60 (standard size)

R2 = 90 Ω cost = $0.90 (standard size)

R3 = 100 Ω, cost = $0.75 (nonstandard size)

The system should be designed for minimum cost such that lies within the range I = 1.2 A ± 5 percent.

Figure 2.124