<PRE><B>Question 1051684</B>
 a truck with a heavy load drove from boston to New york at a speed of 40 mph. After unloading, it returned from New york to boston at a speed of 60 mph. What was the average speed for the whole trip 
B to NY DATA:
rate = 40 mph ; distance = x miles ; time = d/r = x/40 hrs
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NY to B DATA:
rate = 60 mph ; distance = x miles ; time = d/r = x/60 hrs
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Average speed = (total distance)/(total time) = 2x/(x/40 + x/60)
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= (2x)/(60x + 40x)/(40*60)
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= (2x)/[100x/2400]
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= 2/(1/24)
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= 48 mph
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Cheers
Stan H.
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