Question

Lamp manufacturer's specifications for a 40W fluorescent lamp indicate an output of 2680 lumens a rated life of 20,000 hr, and a cost of S5.20 per lamp. Data for a 150W incandescent lamp indicates an output of 2,850 lumens, a rated life of 750 hr, and a cost of $2.30 per lamp. When in use, it is anticipated that these lamps will be operated 14 hr per day, 280 days per year Approximate the energy ($0.10/kWh) and replacement costs (neglect labor costs) of each type of lamp over a 10-year period. Assume use and lamp costs remain constant.

Answer 1

$\implies \text{Total cost is }156.8\$+10.40\$=167.2\$ \\ (a)\text{Second case incandescent lamp} \\ \text{Power output is 150W} \\ \text{Energy output for 10 years is Power *time = }150*39200 \ Wh \\ =150*39.2 \ KWh=5880 \ KWh \\ \text{Energy Cost is }0.10*5880\$=588\$ \\ \text{Nos of lamps used is }\Big[\frac{39200}{750}\Big]+1=53 \text{ ([x] is the greatest integer function)}\\ \implies \text{Lamp cost is }53*2.30$=121.90\$ \\$ $\implies \text{Total Cost is }588\$+121.90\$=709.90\$$