A train leaves San Diego at 1:00 PM. A second train leaves the same city in the same direction at 3

Discussion in 'Calculator Requests' started by math_celebrity, Sep 20, 2018.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    A train leaves San Diego at 1:00 PM. A second train leaves the same city in the same direction at 3:00 PM. The second train travels 30mph faster than the first. If the second train overtakes the first at 6:00 PM, what is the speed of each of the two trains?

    Distance = Rate x Time

    Train 1:
    d = rt
    t = 1:eek:o PM to 6:00 PM = 5 hours
    So we have d = 5r

    Train 2:
    d = (r + 30)t
    t = 3:eek:o PM to 6:00 PM = 3 hours
    So we have d = 3(r + 30)

    Set both distances equal to each other since overtake means Train 2 caught up with Train 1, meaning they both traveled the same distance:
    5r = 3(r + 30)

    Multiply through:
    3r + 90 = 5r

    Run this equation through our search engine, and we get r = 45. This is Train 1's Speed.

    Train 2's speed = 3(r + 30).
    Plugging r = 45 into this, we get 3(45 + 30).
    3(75)
    225
     

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