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Math Help - Tough Word Problem.

  1. #1
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    Tough Word Problem.

    A particular disc can be made to rotate at 2 different speeds. If it were made to rotate slower by 135 revolutions per hour, it would require an additional 2.7-hour to make 315 revolutions. Find the higher speed at which it can operate.
    Last edited by mr fantastic; October 25th 2010 at 11:41 AM. Reason: Edited title.
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    Quote Originally Posted by Arka View Post
    A particular disc can be made to rotate at 2 different speeds. If it were made to rotate slower by 135 revolutions per hour, it would require an additional 2.7-hour to make 315 revolutions. Find the higher speed at which it can operate.
    let \omega be the higher speed of rotation in rev/hr

    t = time in hrs to rotate 315 rev at the higher speed

    \omega t = 315

    (\omega - 135)(t+2.7) = 315

    solve the system of equations for \omega ... I'd start by using the first equation and solving for t in terms of \omega, then substitute for t in the second equation.
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