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1. The chandelier in my living room uses four 60W light bulbs. The chandelier is

ID: 3161941 • Letter: 1

Question

1. The chandelier in my living room uses four 60W light bulbs. The chandelier is on for an average of eight hours every day. The light bulbs are incandescent and provide 800 lumens of light each.

a) Use the web to research the average lifetime of this type of bulb and then determine the total cost for me to use incandescent bulbs for ten years. Include in the total cost both the cost of purchasing new bulbs as they burn out and the electricity when they are on.

b) What is the ten year cost if these were LED bulbs instead of incandescents?

Explanation / Answer

Cost of one KWH = 0.12 cent

FOR incandescent bulbs

number of hours of operation = 10 x 365 x 8 = 29200 hr

Energy used = 29200 x 60 /1000 = 1752 KWH

Length of life time of each bulb = 1000 hr

Number of bulbs necessary = 29200 / 1000 = 29.2

cost of bulbs = 29.2 x 1 $ = 29.2 $

Total cost ( Energy + bulbs) = 29.2 + ( 1752 x 0.12 ) = 239.44 $

Number of bulbs = 4

Total cost for 4 bulbs = 957.76 $

For LED bulbs

A 10 W LED bulb provides 800 Lumen of light.

number of hours of operation = 10 x 365 x 8 = 29200 hr

Energy used = 29200 x 10 /1000 = 292 KWH

Length of life time of each LED bulb = 30000 hr

Number of bulbs necessary = 29200 / 30000 = 1 approx

cost of bulb = 1 x 36 $ = 36 $

Total cost ( Energy + bulbs) = 36 + ( 292 x 0.12 ) = 71.04 $

Number of bulbs = 4

Total cost for 4 bulbs = 284.16 $