Question

To save energy and money, Jackie Smith replaced the 150 Watt incandescent light bulb in her house with a 32 Watt CFL bulb. The expected life of incandescent and CFL bulbs is 1000 and 8000 hours respectively. The purchase price of an incandescent bulb is $0.70 and for the CFL it is $5.71. The cost of electricity is 5 cents per kWh. What is her total savings over the life time of the CFL

Answer 1

Answer:

total savings using CFL light bulbs = $47.09

Explanation:

We can compare the costs of 8,000 hours of lighting:

incandescent light  bulbs

• you need 8 incandescent light bulbs to generate 8,000 hours of lighting = 8 x $0.70 = $5.60
• they will consume a total of 150 watts x 8,000 hours = 1,200 kWh x $0.05 per kWh = $60
• total cost = $5.60 + $60 = $65.60

CFL light bulbs

• you need one CFL light bulb to generate 8,000 hours of lighting = $5.71
• it will consume a total of 32 watts x 8,000 = 256 kWh x $0.05 = $12.80
• total cost = $5.71 + $12.80 = $18.51

total savings = $18.51 - $65.60 = -$47.09