Hi there! Okay I have a two Physics questions. This is for the detailed study 'Investigating energy alternatives'. It is year 11 work.

Calculate the amount of electrical energy converted in you classroom in one school year. If a typical price for electricity is 17 cents per kilowatt-hour, what is the running cost of the lights in your room? Identify any simplifying assumptions you have made for the purposes of calculation.

*This question has only given me "...17 cents per kilowatt-hour..." to work with. I don't understand how I can solve this. Do I have to break the answer down some how to give me more to work with? Or do I have to add additional information to solve this?*

A car converts 3.3*10^7 J of the energy stored in each litre of petrol. The efficiency of the energy conversion to the mechanical energy that keeps the car in motion is 25%. The car burns 10 L of petrol for every 100 km/h. What is the mechanical power output at that speed?

Okay I have no idea what to do in the above questions. If anyone could provide help, hints or just supply complete explanations to solve this it would be appreciated!