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Math Help - Word Problem.

  1. #1
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    Word Problem.

    Alright, here is the problem-
    Flying against the jetstream, a jet travels 3500km in 5 hours. Flying with the jetstream, the same jet travels 6580km in 7 hours.

    What is the speed of the jet in still air, and what is the speed of the jetstream?

    So going against the jetstream, the jet gets about 700km/h.
    And going with the jetstream, the jet gets 940km/h.

    So, how do I find the speed of the jet if there is NO jetstream, and then the speed of the jetstream?

    Thanks!

    I'm sure this is way less complicated than I am making it seem to be.
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  2. #2
    Senior Member topher0805's Avatar
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    Ok, you have already figured out the speed of the jet going both directions and I will trust that you have done those correctly.

    With the jetstream = 940 km/h

    Against the jetstream = 700 km/h

    Let's call the speed of the jet x and the speed of the jetstream y.

    When traveling with the jetstream:

    x+y=940

    When traveling against the jetstream:

    x-y=700

    We know that the absolute speed of the jet is the same in both cases, so let's isolate x in the first equation:

    x = 940 - y

    Now sub that into the second equation:

    (940-y)-y=700

    Solve for y, then sub that value into either of the first two equations to solve for x.
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  3. #3
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    Okay, so I figure the jetstream to equal 120km/h and the speed of the Jet at 820km/h.

    Am I right? (just making sure)
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  4. #4
    Senior Member topher0805's Avatar
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    Yes you are right, assuming that the velocities you calculated are correct.
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