Question

isaiah is trying to decide if the interval use plan is better than the standard use plan for his electricity consumption. calculate the monthly costs of both plans if he uses 1,275 kwh of electricity per month with 575 kwh on - peak usage and the rest off - peak usage.

standard use plan	interval use plan
10 cents/kwh for anything over 400 kwh	off - peak hours - 3 cents/kwh

a. standard use plan - $117.50; interval use plan - $107.25
b. standard use plan - $87.50; interval use plan - $86.25
c. standard use plan - $117.50; interval use plan - $86.25
d. standard use plan - $87.50; interval use plan - $107.25

Explanation:

Step1: Calculate cost for standard use plan - first 400 kWh

Cost for first 400 kWh is $0.075\times400 = 30$ dollars.

Step2: Calculate amount of electricity over 400 kWh

$1275 - 400=875$ kWh.

Step3: Calculate cost for electricity over 400 kWh in standard use plan

Cost for remaining electricity is $0.1\times875 = 87.5$ dollars.

Step4: Calculate total cost for standard use plan

Total cost is $30 + 87.5=117.5$ dollars.

Step5: Calculate cost for on - peak usage in interval use plan

Cost for on - peak usage is $0.15\times575 = 86.25$ dollars.

Step6: Calculate amount of off - peak usage

Off - peak usage is $1275 - 575 = 700$ kWh.

Step7: Calculate cost for off - peak usage in interval use plan

Cost for off - peak usage is $0.03\times700 = 21$ dollars.

Step8: Calculate total cost for interval use plan

Total cost is $86.25+21 = 107.25$ dollars.

Answer:

a. standard use plan - $117.50; interval use plan - $107.25