Question

In a certain city, electricity costs $0.13 per kW·h.

What is the annual cost for electricity to power a lamp-post for 7.50 hours per day with (a) a 100.-watt incandescent light bulb (b) an energy efficient 25-watt fluorescent bulb that produces the same amount of light? Assume 1 year = 365 days.

(a) 100.-watt bulb
(b) 25-watt bulb

Answer 1

Part a)

cost = $35.58

Part b)

cost = $8.89

Step-by-step explanation:

Part a)

Annual cost of the incandescent light bulb

Power = 100 Watt

daily use = 7.5 hours

total use of one year

`Energy = 100 * 7.5 * 365`

`Energy = 273750 Wh`

`Energy = 273.75 kWh`

cost of energy = $0.13 per kWh

so total cost of energy = $0.13 (273.75)

cost = $35.58

Part b)

25 watt fluorescent bulb

Power = 25 Watt

daily use = 7.5 hours

total use of one year

`Energy = 25 * 7.5 * 365`

`Energy = 68437.50 Wh`

`Energy = 68.437 kWh`

cost of energy = $0.13 per kWh

so total cost of energy = $0.13 (68.437)

cost = $8.89

Answer 2

The question is asking to compute the annual cost of electricity to power a lamp post for 7.5 hrs per day with the following power, and base on my calculation, the answers would be the following:
#1. 7,580,769.23
#2. 1,895,195.31
I hope you are satisfied with my answer and feel free to ask for more if you have questions and further clarifications.