In an electricity pricing system based on time-of-day, where rates vary between peak and off-peak hours, let's analyze a situation where the electricity cost is \$0.21/kWh from 7:00 a.m. to 10:00 p.m. and \$0.09/kWh at all other times. What will be the yearly expense for electricity if a 3.5 kW air conditioner operates daily from 4:00 a.m. to 8:00 p.m.?
