Question

One freezer costs $623.95 and uses 90 kilowatt hours (kwh) of electricity each month. A second freezer costs $500 and uses 100 kwh of electricity each month. The expected life of each freezer is 12 years. What is the minimum electric rate in cents per kwh for which the 12-year total cost (purchase price + electricity costs) will be less for the first freezer?

Answer 1

Answer: b on edge... its 8.608

Step-by-step explanation: i took the test

Answer 2

Let x = minimum electric rate (Cents/kWh)
Total months in 12 years is 12*12 = 144 m

1st freezer
Total cost over 12 years is
623.95 (cost) + (90 kWh/m)*(144 m)(x/100 $/kWh)
= 623.95 + 129.6x

2nd freezer
Total cost over 12 years is
500 + 100*144*(x/100)
= 500 + 144x

For the 1st freezer to cost less over 12 years,
623.95 + 129.6x < 500 + 144x
123.95 < 14.4x
8.61 < x

Answer: The minimum rate is 8.61 cents per kWh