document.write( "Question 451180: A cyclist bikes x distance at 10 miles per hour and returns over the same path at 8 miles per hour. What is the cyclist's average rate for the round trip in miles per hour?
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\n" ); document.write( "\n" ); document.write( "I know with averages you add the groups of numbers and then divide by the number of groups. I came up with e)9. I must be missing something because the answer key says that the correct answer is d)8.9. I need to know if the answer key is wrong or if I am doing something wrong. Please show the detailed solution if i am doing something wrong. \n" ); document.write( "

Algebra.Com's Answer #310271 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!

 
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document.write( "Hi,
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document.write( "A cyclist bikes x distance at 10 miles per hour 
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document.write( "and returns over the same path at 8 miles per hour. (total distance is 2x)
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document.write( "Average rate = total distance/total time:  
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document.write( "Note t = D/r  t(going) = x/10mph,  t(returning) = x/8mph
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document.write( "Average rate =   
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document.write( "For ex: If the cyclist went 40mi and biked back... 
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document.write( " Average rate = total distance/total time =  80/(40/10 + 40/8) = 80/(4+5) = 80/9
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