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Plunk and Ms. Q run a 100-meter race. Plunk runs at 8 meters per second, and Ms. Q runs at 5 meters per second. Because Ms. Q runs slower, she is given a 3-second head start. Plunk wins the race. How much time, in seconds, is it between the time Plunk passes Ms. Q and the time that Plunk finishes the race?

 Mar 5, 2021
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3 second head start =   3x 5 = 15 meters

    difference in speed   8- 5 = 3 m/s           15 / 3 = 5 seconds when P catches Q    (this 8 seconds after Q starts)

 

in 5 seconds P runs   5 * 8 = 40 meters   this is when they are at the same point 

                    60 meters left in the race   will take  P     60 m / 8 m/s = 7.5 seconds to finish

 Mar 5, 2021

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