document.write( "Question 252745: I have one last problem that seems simple enough, but I can't come up with the answer that is given. Could you please show me what I'm missing here? The answer given is: 8.9 , I'm thinking 9 . The problem: 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?
\n" ); document.write( " Once again, thanks Daniel \n" ); document.write( "

Algebra.Com's Answer #184822 by Alan3354(69443) $\"\"$ $\"About$

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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( "d= rt --> t = d/r
\n" ); document.write( "t = x/10 + x/8 = 9x/40
\n" ); document.write( "r = 2d/t = 2x/t --- 2x for the round trip
\n" ); document.write( "r = (2x/1)/(9x/40) = 80x/9x
\n" ); document.write( "r = 80/9 = 8.888... mph
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\n" ); document.write( "It's not the average, 9 mph, because he spent more time going 8 mph than he did going 10 mph.
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\n" ); document.write( "That's the basis of the famous Michelson-Morley experiment that disproved the existence of the \"ether\" is space. \n" ); document.write( "

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