An energy efficient light bulb uses 15 W of power for an equivalent light output of a 60 W incandescent light bulb.How much money do you save each month by using the energy efficient light bulb instead of the incandescent light bulb for 6 hours a day? Assume that 1 kW.hr costs 14 cents and there are 30 days in one month.
A)$0.39
B)$0.76
C)$1.51
D)$0.57
E)$1.13

Question

Quizplus · Accepted Answer

First, calculate the power saved by using the energy-efficient bulb: 60W - 15W = 45W. Convert this to kW: 45W = 0.045kW. Calculate the energy saved per day: 0.045kW * 6 hours = 0.27kWh. For a month (30 days), the total energy saved is 0.27kWh/day * 30 days = 8.1kWh. At a cost of 14 cents per kWh, the monthly savings is 8.1kWh * $0.14/kWh = $1.134. Rounding to the nearest cent gives $1.13.

An Energy Efficient Light Bulb Uses 15 W of Power