The average cost of electricity used for an 18 cubic ft. refrigerator that is 10 years old is $128 per year. A new refrigerator the same size costs about $81 per year for electricity. (Source: https://www.efficiencyvermont.com)

1. Suppose a new refrigerator costs $500. Determine the total cost of having either refrigerator for 12 years, assuming the only costs associated with the refrigerator are its purchase cost and electricity.
2. Determine the total annual cost for a new refrigerator that lasts 12 years, assuming the only costs associated with the refrigerator are its purchase cost and electricity.
3. Write a function that gives the annual cost of a new refrigerator as a function of the number of years you own the refrigerator.
4. What are the asymptotes of the rational function in part d? What does the horizontal asymptote mean in the context of this problem?
5. Sketch the graph of the rational function from part c.
6. If you plan on owning your refrigerator for 12 years, would it be more cost effective to keep your old refrigerator or purchase a new one? Explain.