43. •• A 120-V air conditioner unit draws 15 A of current.

If it operates for 20 min,

(a) how much energy in kilowatt-

hours does it require in that time?

(b) If the cost of electricity is $0.15/kWh, what is the cost of operating it for 20 min?

(c) If the air conditioner initially cost

$450 and it is operated, on average, 4 h per day, how long does it take before the operating costs equal the price?