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Homework Help: Rational Expression Word Problem

  1. May 14, 2006 #1
    In a motorcycle race, one lap of the course is 650m. At the start of the race, Genna sets off 4 seconds after Tom does, but she drives her motorcycle 5m/s faster and finishes the lap 2.5 seconds sooner than he does.

    a) Find the speed at which each of them is driving.

    b) Find the tim etaken by each of them to cover the distance.

    How I started this problem

    Let x be Genna's time if she started at the same time

    time =x
    distance =650
    speed = 650/x


    time = x +2.5
    distance =650 m
    speed = x +2.5

    then i did 650/x - 650/x+2.5 = 5m/s

    this generated the wrong answers

    here are the correct answers

    a)Tom 20m/s Genna 25.0m/s
    b) Tom 32.5 s Genna 6s


  2. jcsd
  3. May 14, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You forgot to take into account that Genna started 4 seconds after Tom. Also Tom's speed is not given by;
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