document.write( "Question 175252: Barbara and Ramir raced each other. Barbara averaged 9 mph for the entire course while Ramir averaged 8 mph for the fist half of the course and 10 mph for the second half. Who won? \n" ); document.write( "
Algebra.Com's Answer #130349 by gonzo(654)\"\" \"About 
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it appears that barbara is the winner.
\n" ); document.write( "here's why:
\n" ); document.write( "---
\n" ); document.write( "let t = time it took barbara.
\n" ); document.write( "since rate * time = distance, then
\n" ); document.write( "9*t = d
\n" ); document.write( "which means that
\n" ); document.write( "t = d/9
\n" ); document.write( "barbara took d/9 hours to cover the distance.
\n" ); document.write( "---
\n" ); document.write( "let t1 = time it took ramir to cover half the distance at 8 mph.
\n" ); document.write( "since rate * time = distance, then
\n" ); document.write( "8*t1 = d/2
\n" ); document.write( "which means that
\n" ); document.write( "t1 = d/16
\n" ); document.write( "---
\n" ); document.write( "let t2 = time it took ramir to cover half the distance at 10 mph.
\n" ); document.write( "since rate * time = distance, then
\n" ); document.write( "10*t2 = d/2
\n" ); document.write( "which means that
\n" ); document.write( "t2 = d/20
\n" ); document.write( "---
\n" ); document.write( "the total time it took ramir is equal to t1 + t2.
\n" ); document.write( "since t1 = d/16 and t2 = d/20, then
\n" ); document.write( "t1 + t2 = d/16 + d/20
\n" ); document.write( "---
\n" ); document.write( "d/16 + d/20 = (20d + 16d) / (16*20)
\n" ); document.write( "which equals
\n" ); document.write( "36d / 320
\n" ); document.write( "which equals
\n" ); document.write( "d/8.888888888..... hours
\n" ); document.write( "---
\n" ); document.write( "t1 + t2 = d/8.8888888.... hours which is the time it took ramir.
\n" ); document.write( "---
\n" ); document.write( "since d/9 is a smaller number than d/8.8888888....., this means that barbara is the winner.
\n" ); document.write( "---
\n" ); document.write( "this answer should be good at any distance.
\n" ); document.write( "as an example, let d = 90
\n" ); document.write( "it took barbara 10 hours
\n" ); document.write( "it took ramir 10.125 hours.
\n" ); document.write( "this is 45/8 + 45/10 since he covered half the distance at 8 mph and half the distance at 10 mph.
\n" ); document.write( "---
\n" ); document.write( "let d = 1500 miles
\n" ); document.write( "it took barbara 166.7 hours (rounded)
\n" ); document.write( "it took ramir 168.75 hours.
\n" ); document.write( "this is 750/8 + 750/10 since he covered half the distance at 8 mph and half the distance at 10 mph.
\n" ); document.write( "---
\n" ); document.write( "answer checks out ok.
\n" ); document.write( "barbara is the winner at any distance.
\n" ); document.write( "
\n" );