It is currently popular for automobiles to use 10% ethanol / 90%gasoline mixtures (‘gasohol’) as fuel. According topopular consensus the main benefit of gasohol use is that it“reduces our dependence upon foreign oil.” Test thisassertion by making some elementary calculations. Our analysis willunrealistically ignore engine maintenance issues associated witholder automobiles (such as gasket and seal hardening), the addedfuel consumption necessary to produce grain used as a feedstock inethanol production, the incremental food price increases associatedwith a reduction in grain stocks, and many other important effects.Gasohol use typically reduces average fuel economy by approximately15% and effectively leaves fuel prices unchanged.

Determine the ‘break-even’ fueleconomy ratio – that is, find the ratio of the gasoline to gasohol fuel economy for two vehicles to use the same amount ofpure gasoline when driven the same distance?