The monthly (30 days) electric bill included the cost of running a central air-conditioning unit for 2.0 hr/day at 5000 W, and a series connection of ten 60 W light bulbs for 5.0 hr/day. How much did these items contribute to the cost of the monthly electric bill if electricity costs 8.0¢ per kWh?

Question

Quizplus · Accepted Answer

The air-conditioning unit uses 5000 W for 2 hours per day, which is 10 kWh/day. The light bulbs use 600 W (10 bulbs x 60 W) for 5 hours per day, which is 3 kWh/day. Total daily usage is 13 kWh. Over 30 days, this is 390 kWh. At 8.0¢ per kWh, the cost is $31.20.

The Monthly (30 Days) Electric Bill Included the Cost of Running