SOLUTION: A certain car uses 15 gal of gasoline in 3 h. If the rate of gasoline consumption is constant, how much gasoline will the car use on a 35-hour trip?

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Question 1202459: A certain car uses 15 gal of gasoline in 3 h. If the rate of gasoline consumption is constant, how much gasoline will the car use on a 35-hour trip?
Found 4 solutions by ikleyn, greenestamps, josgarithmetic, math_tutor2020:
Answer by ikleyn(52852) About Me  (Show Source):
You can put this solution on YOUR website!
.

Write a proportion

    gallons%2Fhours = 15%2F3 = x%2F35.


From this proportion, find  x = %2815%2A35%29%2F3 = 5*35 = 175 gallons.    ANSWER

Solved.

Notice that the proportion says that the rate of the gasoline consumption per hour remains the same (remains constant).

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For introductory lessons on proportions,  see the lessons
    - Proportions
    - Using proportions to solve word problems
    - Typical problems on proportions
    - Using proportions to estimate the number of fish in a lake
    - HOW TO algebraize and solve these problems using proportions
in this site.

Learn the entire subject from there.


Happy learning  ( ! )



Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


Using a proportion, as the other tutor did, is one good formal way for solving the problem.

A slightly less formal way, given that the rate of fuel consumption is constant, is to multiply the given number of gallons of gas by the ratio of the two times:

15%2A%2835%2F3%29+=+%2815%2A35%29%2F3+=+5%2A35+=+175

ANSWER: 175 gallons

And a third easy solution method is to use the given data to determine the rate of fuel consumption in gallons per hour and multiply that number by 35 hours:

15%2F3=5
5%2A35=175

The actual calculation in all three solution methods is the same; so the choice of which method is up to the student -- find the method that "works" for you an use it.

Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
15 gallons fuel in 3 hours;
35 hours of travel ;


35%2Ahours%2A%2815%2F3%29%28gallons%2Fhours%29

%28%2835%2A15%29%2F3%29gallons

%2835%2A3%2A5%29%2F3 gallons

35%2A5gallons

175%2Agallons

Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

Answer: 175 gallons

Work Shown
15 gal : 3 hr
15/3 gal : 3/3 hr .... divide both sides by 3
5 gal : 1 hr
35*5 gal : 35*1 hr .... multiply both sides by 35
175 gal : 35 hr