A group of enterprising engineering stu- dents has developed a process for extracting combustible methane gas from cow manure (don't worry,the exhaust is odorless).With aspecially adapted internal combustion engine, the students claim that an automobile can be propelled 15 miles per day from the "cow gas" produced by a single cow. Their

experimental car can travel 60 miles per day for an esti- mated cost of$5(this is the allocated cost of the methane process equipmentthe cow manure is essentially free). (2.1)

a) How many cows would it take to fuel 1,000,000 miles of annual driving by a eet of cars? What is the annual cost? b. How does your answer to Part (a) compare to a gasoline-fueled car averaging 30 miles per gallon when the cost of gasoline is $3.00 per gallon?