An electric heater of 1000 W is used for 2 h a day. What is the cost of using it for a month of 28 days, if 1 unit costs Rs 3?

Energy consumed by heater of 1000 W for 2 h in one

day =1000/1000 X 2 = 2 units

Number of units = Watt x hours x day / 1000

Energy consumed by heater in 28 days = 2 x 28 = 56 units.

Cost of 1 unit= Rs 3

Cost of 56 units = 3 x 56 = Rs 158