<PRE><B>Question 311659</B>
A car travels up a hill at a constant speed of 35 km/h and returns down the hill at a constant speed of 67 km/h. Calculate the average speed (in km/h) for the round trip. 
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UP DATA:
rate = 35 km/h ; time = x hrs ; distance = 35x km
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Down DATA:
rate = 67 km/h ; time = y hrs ; distance = 67y  km
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Average speed = (total distance)/(total time)
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Ave speed = (35x+67y)/(x+y) km/h
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cheers,
Stan H.</PRE>