Pure gasoline has an energy density of 115600 BTU per gallon

Pure gasoline has an energy density of 115,600 BTU per gallon, while ethanol has an energy density of 75,670 BTU per gallon. Gasoline costs $2.8 per gallon. What would the cost of pure ethanol have to be in order for the energy costs of the two fuels to break even? The cost of pure ethanol is determined to be $________ .

Solution

At break even, total cost of pure gasoline = total cost of ethanol

115600*2.8 = 75670*x

Where x= cost of pure ethanol

x= 115600*2.8/75670= 4.277

Cost of pure ethanol is determined to be 4.277 per gallon.