Obviously, from the point view of efficiency, the higher the EER the better, but a higher EER is typically accom higher price. Consider two 12,000-Btu air conditioners, one with an EER of 7.8 and the other with a EER of 10. The difference in price is about 70 dollars. Assuming that the air conditioner will be operated for 6 hours daily during a period of 4 months every year, how long will it take to break even financially if you purchase the more expensive unit? Take the electricity to be 0.10dollar/(kilowatt. Hour). a) Less than a year b) about two year c) about three year d) about four year e) more than five years