SOLUTION: Solve the problem. When Mary's car's tire pressure is 30 pounds per square inch (psi), it averages 20.8 mpg of gasoline. If the tire pressure is increased to 35 psi, the car averag

Algebra ->  Test -> SOLUTION: Solve the problem. When Mary's car's tire pressure is 30 pounds per square inch (psi), it averages 20.8 mpg of gasoline. If the tire pressure is increased to 35 psi, the car averag      Log On


   



Question 305389: Solve the problem. When Mary's car's tire pressure is 30 pounds per square inch (psi), it averages 20.8 mpg of gasoline. If the tire pressure is increased to 35 psi, the car averages 21.6 mpg of gasoline. If Mary drives an average of 20,000 miles per year, how many gallons of gasoline will she save in one year by increasing her tire pressure from 30 psi to 35 psi (round to the nearest unit)? Show your step by step work!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!

Just looking at the units and no numbers:
(miles driven) / (mi/gal) = gallons consumed
--------------------------------------------
20000%2F21.6+=+925.926 gallons consumed in a year
20000%2F20.8+=+961.538 gallons consumed in a year
961.538+-+925.926+=+35.612
She saves 36 gallons in a year by increasing tire pressure