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Math Help - we gotta problem here guys=("tough Question"

  1. #1
    Junior Member User Name's Avatar
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    Unhappy we gotta problem here guys=("tough Question"

    Hi
    I'm new and it's my first post
    anyways can anyone help me to solve this Question it's really annoying

    How fast?



    Thanks
    Last edited by User Name; May 23rd 2008 at 12:19 AM.
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  2. #2
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    Quote Originally Posted by User Name View Post
    Hi
    I'm new and it's my first post
    anyways can anyone help me to solve this Question it's really annoying

    How fast?


    A spacecraft undergoes a journey of two separate legs. The second leg is twice as long as the first leg, and the average speed of the craft during the second leg is is 10% higher than its average speed during the earlier leg.
    The spacecraft's average speed over the entire journey is 9660 km/h.
    calculate its average speed for each leg.

    Thanks
    Let the average speed in first leg be v and let distance of first leg be x.

    Then average speed in second leg is v + (v/10) = 11v/10 and distance of second leg is 2x.

    Time to travel first leg: t_1 = \frac{x}{v} .... (1)

    Time to travel second leg: t_2 = \frac{2x}{11v/10} = \frac{20 x}{11 v} .... (2)

    Average speed for entire journey: 9660 = \frac{3x}{t_1 + t_2} .... (3)

    Substitute (1) and (2) into (3) and solve for v (note that the x's cancel out).


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