document.write( "Question 726732: How would I solve this question?\r
\n" ); document.write( "\n" ); document.write( "A high speed train travels from Chicago to Denver at an average speed of 90 miles per
\n" ); document.write( "hour, but can make the return trip at an average speed of 110 miles per hour. What is the
\n" ); document.write( "average speed for the round trip?
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Algebra.Com's Answer #444771 by Alan3354(69443)\"\" \"About 
You can put this solution on YOUR website!
A high speed train travels from Chicago to Denver at an average speed of 90 miles per
\n" ); document.write( "hour, but can make the return trip at an average speed of 110 miles per hour. What is the
\n" ); document.write( "average speed for the round trip?
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\n" ); document.write( "d = distance one way
\n" ); document.write( "t = RT time = d/90 + d/110
\n" ); document.write( "RT distance = 2d
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\n" ); document.write( "RT avg speed = 2d/(d/90 + d/110)
\n" ); document.write( "= 2/(1/90 + 1/110) = 2/((90 + 110)/(90*110))
\n" ); document.write( "= 2*90*110/(90 + 110) = 99 mi/hr
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\n" ); document.write( "Avg speed for a round trip = 2*r1*r2/(r1 + r2)
\n" ); document.write( "Distance is not a factor.\r
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