SOLUTION: My question involves a word problem: A certain car that is being tested by its manufacturer uses it entire fuel supply in about 38 hours when idling. The same car, when driven a

Question 106987: My question involves a word problem:
A certain car that is being tested by its manufacturer uses it entire fuel supply in about 38 hours when idling. The same car, when driven at 60 miles per hour on a test track, uses about three-and-a- half times as much fuel per hour as it does when idling. If the engine has been idling for 10 hours and the car is then run at 60 miles per hour, how much longer will the car run before it uses up all of its fuel?
I think it is 38 - 10 = 28 divided by 3.5 = 8 hours.
I just don't know the exact steps to follow to get the correct answer.
Could you please help....
Thank you...
Answer by josmiceli(6786) (Show Source):
You can put this solution on YOUR website!
I get the same answer
What's the rate of using fuel when idling?
(1 tank) / 38 hours
Whats the rate of using fuel at 60 mph?
(3.5 tanks) / 38 hours
Now to use up 1 tankful,
(idle rate*idle time) + (run rate*run time) = 1 tank
{1 tank/38 hours)*10 hours + (3.5 tanks/38 hours)*(run time) = 1 tank

answer