You have a electric heater with 2 modes which is Super and Auto.
If heater is on for 1 hour then it consumes 2 units of power.
You observe that during sleep super mode could heat room in just 2.5 hrs for whole night.
While auto mode requires heater to run whole night during which it starts heat for 60 minutes and then take break for 30 minutes.
Rate of power is 0.75$ per unit.
Choose best option and say what is electricity expense due to heater for December month.