an author spent about 1000h working on her computer that has a power input of 60W. Seventy additional hours were spent with the 60-W computer and the 240-W printer running. How much did it cost for the energy use of these two devices, at a cost of $.100 per kWh?

Question

ujjwal · Answer

Energy in KWh= 60/1000 * 1000 + (60+240)/1000 * 70 =81 KWh = 81* $ 1= $ 81.00
trick: convert W to KW (dividing by 1000) and multiply it with hrs. to get energy in KWh..