document.write( "Question 1195791: The current world record holder in both the 5000 m and 10000 m
\n" ); document.write( "is the Ethiopian runner Kenenisa Bekele. In his career he won
\n" ); document.write( "3 Olympic gold medals and 5 world championships.
\n" ); document.write( "His world record times are: e 12 min 37.35 s for 5000 m
\n" ); document.write( "e 26 min 17.53 s for 10000 m.
\n" ); document.write( "a Kenenisa’s tactic in the 5000 m was to run at a constant speed
\n" ); document.write( "of 6.5 ms™! for most of the race, then sprint the last section at
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\n" ); document.write( "b In the 10000 m, Kenenisa was not able to run quite as fast. He
\n" ); document.write( "ran at 6.3 ms—! for most of the race, then sprinted at 7.5 ms~*
\n" ); document.write( "at the end. At what point did Kenenisa sprint in this race? \n" ); document.write( "

Algebra.Com's Answer #828318 by ikleyn(52790) $\"\"$ $\"About$

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\n" ); document.write( "The current world record holder in both the 5000 m and 10000 m
\n" ); document.write( "is the Ethiopian runner Kenenisa Bekele. In his career he won
\n" ); document.write( "3 Olympic gold medals and 5 world championships.
\n" ); document.write( "His world record times are: e 12 min 37.35 s for 5000 m
\n" ); document.write( "e 26 min 17.53 s for 10000 m.
\n" ); document.write( "a Kenenisa’s tactic in the 5000 m was to run at a constant speed
\n" ); document.write( "of 6.5 ms™! for most of the race, then sprint the last section at
\n" ); document.write( "7.7 ms~!. How far did Kenenisa sprint at the end?
\n" ); document.write( "b In the 10000 m, Kenenisa was not able to run quite as fast. He
\n" ); document.write( "ran at 6.3 ms—! for most of the race, then sprinted at 7.5 ms~*
\n" ); document.write( "at the end. At what point did Kenenisa sprint in this race?
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document.write( "(a)  Let d be \"How far did Kenenisa sprint at the end\", \r\n" );
document.write( "     the unknown value under the problem's question.\r\n" );
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document.write( "     In other words, d is the distance, which Kenenisa Bekele ran at the speed 7.7 m/s.\r\n" );
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document.write( "     Notice that 12 min 37.75 seconds = 12*60 + 37.75 = 757.75 seconds.\r\n" );
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document.write( "     Then we can write this \"time\" equation\r\n" );
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document.write( "          +  = 757.75  seconds.\r\n" );
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document.write( "     To solve it, multiply both sides by the product 6.5*7.7.  You will get\r\n" );
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document.write( "          7.7*(5000-d) + 6.5*d = 757.75*6.5*7.7.\r\n" );
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document.write( "     Simplify and find \"d\"\r\n" );
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document.write( "          7.7*5000 - 7.7d + 6.5d = 37925.3875\r\n" );
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document.write( "                        -1.2d    = 37925.3875 - 7.7*5000\r\n" );
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document.write( "                        -1.2d    =     -574.6125\r\n" );
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document.write( "                            d    =      = 478.84375 meters.\r\n" );
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document.write( "ANSWER.  At the end, Kenenisa ran 478.84 meters (rounded) at the speed of 7.7 m/s.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solve the second problem in the same way,\r
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