document.write( "Question 749075: Two runners start running at the same time from the start/finish line of a 400 meter oval track. One runner runs laps of 1 minute 15 seconds and the other runs laps of 1 minute 45 seconds. How long will it be before the runners cross the finish line at the same time? \n" ); document.write( "

Algebra.Com's Answer #455786 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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Two runners start running at the same time from the start/finish line of a 400 meter oval track.
\n" ); document.write( " One runner runs laps of 1 minute 15 seconds and the other runs laps of 1 minute 45 seconds.
\n" ); document.write( " How long will it be before the runners cross the finish line at the same time?
\n" ); document.write( ":
\n" ); document.write( "Change the times to seconds:
\n" ); document.write( "Runner one laps in 75 sec
\n" ); document.write( "Runner two laps in 105 sec
\n" ); document.write( ":
\n" ); document.write( "Find the least common multiple of 75 and 105 by prime factoring.
\n" ); document.write( "75: 3*5*5
\n" ); document.write( "105: 3*7*5
\n" ); document.write( "LCM: 3*5*5*7 = 525 seconds they will cross the finish line at the same time
\n" ); document.write( "(That's 8 min 45 sec)
\n" ); document.write( ":
\n" ); document.write( "Runner one completes exactly 525/75 = 7 laps
\n" ); document.write( "Runner two completes exactly 525/105 = 5 laps \n" ); document.write( "

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