Question

A set of four "80 - year," fifty (50) watt light bulbs costs ​$24.29. If H equals the annual number of hours the bulb is​ used, each bulb provides 80H hours of​ light, and the efficiency of each bulb is 75%. A set of four, fifty(50​) watt standard bulbs costs ​$2.31. Each standard bulb provides H hours of light and the efficiency of each bulb is 90%. If the cost of electricity is ​$0.0582​/kWh, how many hours of operation each year will make the costs of the two types of bulb breakeven​?

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Answer 1

Given that cost of electrocity = $ 0.0582 /kwh, Total number of bulbs in first set = 5 Total years of usage = 8 voltage of each bulb = 60w Total voltage of bulbs = 300 w Total hours of usage of bulbs = 5 times 80 H = 400 H hours. Total hours of voltage hours = 60 times 80 times H times 5 = 24000 H w-h Efficiency of this total walt-hours = 24000 H times 0.7 = 16800 H = 16.8 H kwh cost of this set of bulbs usage = 16.8 H times 0.0582 = 0.97776 H cost of the bulbs set = $ 24.29 The break even point is the point where the profit is 0. That means the cost investment should be equal to usage 0.97776 H = 24.29 \r\n H = 28.9 Annually this set of bulbs should be used for approximately 29 hours. therefore H = 29 hours