In a certain city, electricity costs $0.13 per kW·h. What is the annual cost for
ID: 929370 • Letter: I
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 5.00 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.
(c) A typical incandescent bulb costs $0.89 and lasts for about a year; a typical energy efficient fluorescent bulb costs about $3.49 and lasts for about 3 years. Is the additional cost of the fluorescent bulb justified?
Explanation / Answer
a) 100 W= 0.1 Kw it runs for 5 hours/ day= 0.1 Kw* *5 hours/ day*365days/ year=182.5Kwhr.
Electricity cost =$0.13 per Kwhr
Total electricity cost= 0.13*182.5=23.725$
Cost of electricity + blub cost=(23.725+ 0.89)*3$ ( for three years=73.845S
b) In case of fluorescent bulb energy cost = 0.025*5*365*0.13 =5.93 $/yer
for three years , cost= 5.93*3 + 3.49 =21.28$
Hence purchase of bulb is worthwihile based on the cost.