# Energy savings question

1. Mar 5, 2016

### theone

1. The problem statement, all variables and given/known data
An advertisement claims a total annual savings in electricity worth 73 million dollars for each Canadian household replacing one 60W incandescent bulb with an equivalent 13W fluorescent bulb. If the typical total cost of electricity (averaged across Canada) is 8.0 cents per kW-hr, how many hours per day must the replacement and original light bulb be left switched on (on average over the year)?Use the following assumptions: there are 13.3 million residential households in Canada

2. Relevant equations

3. The attempt at a solution
I need some help understanding the question:
"how many hours per day must the replacement and original light bulb be left switched on (on average over the year)?" ...... in order to achieve what?

2. Mar 5, 2016

### Staff: Mentor

In order that powering the lower wattage bulb will cost \$73mil less than for powering the higher wattage bulb----for the same number of hours.

3. Mar 6, 2016

### Staff: Mentor

Thread temporarily closed to further help, being a homework question with no working.

theone
should PM me if there is more to be added to this thread