SOLUTION: The transcontinental train travels from Colorado to Illinois at average speed of 100km/h. If the train had averaged 20km/h less, the trip would have taken 5h longer. How far is it

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Question 1145630: The transcontinental train travels from Colorado to Illinois at average speed of 100km/h. If the train had averaged 20km/h less, the trip would have taken 5h longer. How far is it by train from Colorado to Illinois?
Found 2 solutions by ikleyn, josgarithmetic:
Answer by ikleyn(52814)   (Show Source): You can put this solution on YOUR website!
.

Let "d"  be the distance under the question.


If travels with the average speed of 100 km/h, the travel time is   hours.


If travels with the average speed of 80 km/h, the travel time is   hours.


The difference is 5 hours


     -  = 5  hours.


It is your "time" equation.


As soon as you get it, the setup is completed.


To solve the equation, multiply both sides by 400. You will get


    5d - 4d = 5*400

     d      = 2000 miles.


ANSWER.  The distance is 2000 miles.


CHECK.    = 20 hours.    = 25 hours.

         The difference is  25 - 20 = 5 hours.   ! Correct !

Solved.

----------------

Using  "time"  equation is the  STANDARD  method of solving such problems.

From my post,  learn on how to write,  how to use and how to solve a  "time"  equation.

To see many other similar solved problems,  look into the lessons
    - Had a car move faster it would arrive sooner
    - How far do you live from school?
    - Earthquake waves
    - Time equation: HOW TO use, HOW TO write and HOW TO solve it
in this site.


Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
                     SPEED       TIME        DISTANCE

ACTUAL                 100        d/100         d

HYPOTHETICAL            80        d/80          d

DIFFERENCE                         5



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