Answer:
c. $178.
Explanation:
We have been given that Hanna is on a standard use plan that has a graduated fee schedule. Standard Use Plan 8.5 cents/kWh for the first 400 kWh. 12 cents/kWh for the next 400 kWh and 14.5 cents/kWh for anything over 800 kWh.
The cost of first 400 kWh will be:
The cost of the next 400 kWh will be:

The remaining units of electricity will be
.
The cost of remaining 665 kWh will be:




Therefore, the total cost of Hanna's electricity bill will be $178 and option c is the correct choice.