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a coast guard ship left the port at 30 mph. four hours later a helicopter was dispatched at 90 mph to intercept the ship. how long will it take the helicopter to catch the ship?

  • math -

    Make a chart for the pieces of RT=D that you know.

    Rate X Time = Distance
    _____________________________________
    ship 30 x 30x
    chopper 90 x-4 90(x-4)

    You know that at the time the helicopter overtakes the ship that the distances are equal.

    30x=90(x-4) set distances equal
    30x = 90x-360 ditribute
    -60x = -360 subt 90xfrom both sides
    x =6 divide by -60

    x-4 is the helicopter's time so plug in
    6 for x

    6-4 = 2

    therefore the helicopter will take over
    in 2 hours.

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