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Distance Rate Time Formula Memorization Shortcut

By on August 31, 2012 in Math Concepts, Rate Problems

When working on Distance-Rate-Time questions, you will inevitably use one of the following three formulas.

1. Distance = (Rate)(Time)

2. Rate = Distance/Time

3. Time = Distance/Rate

Did you know that there’s a quick and easy shortcut for recalling all three formulas?

The shortcut is similar to some of the shortcuts you learned in highschool science. It looks like this:  D/RT (aka, the “DiRT” shortcut).  As you may have guessed, D = distance, R = rate, and T = time.

Can you see all three formulas hiding in the simple fraction D/RT?

Here’s how it works. Let’s say, you need to recall the formula for finding the time it takes to complete a certain trip. Simply take the fraction D/RT and remove the T (for time). This leaves you with D/R. In other words, Time = Distance/Rate.

Similarly, if you need to recall the formula for finding the rate (speed), simply take the fraction D/RT and remove the R (for rate). This leaves you with D/T. In other words, Rate = Distance/Time.

Finally, if you need to recall the formula for finding the distance, take the fraction D/RT and remove the D (for distance). This leaves you with RT. In other words, Distance = (Rate)(Time).

So, instead of memorizing 3 formulas, just remember DiRT, which stands for D/RT.

 

About the Author

Chris Lele has been helping students excel on the GRE, GMAT, and SAT for the last 10 years. He is the Lead Content Developer and Tutor for Magoosh. His favorite food is wasabi-flavored almonds. Follow him on Google+!

2 Responses to Distance Rate Time Formula Memorization Shortcut

  1. Eraj September 1, 2012 at 9:10 pm #

    Hey Chris,
    Thanks for great article I have a question though.
    Could you expand your idea concerning Distance, Rate, Time and expound upon a little different situation when two cars/trains/bicycles etc.
    1. move towards each other from opposite directions..
    2. move from one point to different directions (left -right)..
    Any shortcuts here, sometimes these kinds of problems could be really tough to tackle in 2 minutes
    Thank you for your hard work!
    Eraj

    Reply
    • Chris September 5, 2012 at 4:07 pm #

      Hi Eraj,

      Good question :) . To elaborate:

      1) When two things are moving towards each other from opposite directions, add their respective rates.

      2) When two things are heading in opposite directions from a fixed point, add their respective rates.

      Hope that helps!

      Reply


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