document.write( "Question 1184017: Boris and Michael are jogging around a lake. It takes Boris 6 minutes to complete a lap and
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document.write( "Michael takes 8 minutes. After completing each lap, the boys take a rest, Boris for one minute
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document.write( "and Michael for two minutes. Then they continue jogging. If they started jogging together,
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document.write( "how long, in minutes, does it take until they are next together? \n" );
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Algebra.Com's Answer #814576 by ikleyn(52875) You can put this solution on YOUR website! . \n" ); document.write( "Boris and Michael are jogging around a lake. It takes Boris 6 minutes to complete a lap and \n" ); document.write( "Michael takes 8 minutes. After completing each lap, the boys take a rest, Boris for one minute \n" ); document.write( "and Michael for two minutes. Then they continue jogging. If they started jogging together, \n" ); document.write( "how long, in minutes, does it take until they are next together? \n" ); document.write( "~~~~~~~~~~~~~~~~\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " This problem is non-standard Travel and Distance problem.\r \n" ); document.write( "\n" ); document.write( " The first move/thought is to analyse it as @ankor@dixie-net.com did in his post.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " But the normal state of a person who solves it for the first time, is DO NOT BELIEVE and TO CHECK himself (or herself).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " THEREFORE, I decided to make such a check. My solution is below. Read it attentively.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( "Let make timing Table, showing time/times, when the persons, Boris and Michael, are in the starting point again,\r\n" ); document.write( "while they make their trips around the lake. In the Table, I placed timing, when they achieve this starting point and rest there.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " T A B L E \r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " # of lap 1 2 3 4 5 6 7 8 9 10\r\n" ); document.write( "\r\n" ); document.write( " Boris' time 6-7 13-14 20-21 27-28 34-35 41-42 48-49 55-56 62-63 69-70\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " Michael's time 8-10 18-20 28-30 38-40 48-50 58-60 68-70 \r\n" ); document.write( "\r\n" ); document.write( " # of lap 1 2 3 4 5 6 7\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "We look to find non-zero intersection between the given time intervals, when they rest.\r\n" ); document.write( "\r\n" ); document.write( "Such non-zero / (non-empty) intersection is time period from 48 to 49 minutes, when Boris completed his 7-th lap\r\n" ); document.write( "and Michael completed his 5-th lap.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "ANSWER. First time they are next together is 48 minutes after start.\r\n" ); document.write( "\r \n" ); document.write( "\n" ); document.write( "Solved.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "At t = 28 minutes, they \" are together \" during the time interval which lasts 0 minutes and 0 seconds \r \n" ); document.write( "\n" ); document.write( "(empty intersection of time intervals).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So, according to the context (and common sense), I do not consider this time moment as if \" they are together \".\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |