Question

The cost of electricity in a certain city is 0.08 for each of the first 300 kWh and $0.13 for each kilowatt-hour over 300 kWh. Find the number of kilowatt-hours used by a family that receives a $55.20 electric bill

Answer 1

The answer to your question is: The family consumed = 540 kWh

Explanation:

Data

$ 0.08 for each of the first 300 kWh

$0.13 for each kWh over 300 kWH

Electric bill = $55.20

First, calculate if the family consume more than 300 kWh

300 x 0.08 = $24 that is lower than $55.2 so they consume more than 300 kWh

Calculate the difference between what they pay and the cost of 300 kWh

$55.20 - 24 = $ 31.2

Now, rule of three

1 kWh ----------------- $0.13

x ----------------- $31.2

x = (31.2)(1) / 0.13 = 240 kWh

The family consumed = 300 + 240 = 540 kWh