Part A. If the mass of 1.0 kg of coal (or any substance) could be completely converted into energy, how many kilowatt-hours of energy would be produced? Express your answer using two significant figures.
Part B. Assume that the average U.S. family of four uses 700 kWh of electric energy each month and that modern power plants are 33% efficient in converting this released energy into electric energy. How long would this mass be able to supply the U.S. public with electric energy? Express your answer using two significant figures. (Answer in Days)