Question

If a kilowatt-hour of energy costs 75 cents, how much does it cost to leave a 40-watt light bulb on for the entire month of May

Answer 1

May has 31 days
31 x 24 = 744 hours in may
744 x 40 = 29760 watt hours
29760 watt hours = 29.76 kwh 
29.76 x 75 = 2232 cents
2232 cents = $22.32