<PRE><B>Question 531232</B>
Your brother competed in a long bicycle race. 
For the 1st half of the race he averaged 20 mi/h.
DATA: rate = 20mph ; distance = x miles ; time = x/20 hrs
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For the 2nd half of the race he averaged 13 mi/h.
DATA: rate = 13 mph ; distance = x miles ; time = x/13 hrs
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What is his average speed in miles per hour for the whole race? 
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Average = total distance/total time
Ave = (2x)/[(x/20)+(x/13)] 
Ave = (2x)/(33x/(260))
Average speed  = 520/33 mph = 15.76 mph
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Cheers,
Stan H.
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