Question 664178: a car moved for half the distance at a speed of 55 mph and the other half the distance 75 mph. what is the average speed?
Show ALL work Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! a car moved for half the distance at a speed of 55 mph and the other half the distance 75 mph. what is the average speed?
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1st half DATA:
rate = 55 mph ; distance = x miles ; time = x/55 hrs
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2nd half DATA:
rate = 75 mph ; distance = x miles ; time = x/75 hrs
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Average speed = (total distance)/(total time) = (2x)/(x/55+x/75)
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= (2x)/[(75x+55x)/55*75)] = (2*55*75x)/(120x) = 68.75 mph
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Cheers,
Stan H.
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