document.write( "Question 532793: a particular pipe can fill a tank in 7 hours. when a second pipe is added, the tank can be filled in only 2 hours. how long would it take the second pipe to fill the tank by itself? express your answer in hours and minutes \n" ); document.write( "

Algebra.Com's Answer #350919 by Edwin McCravy(20060) $\"\"$ $\"About$

You can put this solution on YOUR website!
a particular pipe can fill a tank in 7 hours. when a second pipe is added, the tank can be filled in only 2 hours. how long would it take the second pipe to fill the tank by itself?
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document.write( "Make this chart, putting x for the hours required for the 2nd pipe alone,\r\n" );
document.write( "since that's what we are to find:\r\n" );
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document.write( "                           number of        hours       rate in\r\n" );
document.write( "                         tanks filled    required     tanks/hour     \r\n" );
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document.write( "1st pipe alone\r\n" );
document.write( "2nd pipe alone                               x\r\n" );
document.write( "both pipes together\r\n" );
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document.write( "Fill in 7 for the hours required for the first pipe alone.\r\n" );
document.write( "Fill in 2 for the hours required for both pipes together.\r\n" );
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document.write( "                           number of        hours       rate in\r\n" );
document.write( "                         tanks filled    required     tanks/hour     \r\n" );
document.write( "-----------------------------------------------------------------\r\n" );
document.write( "1st pipe alone                               7\r\n" );
document.write( "2nd pipe alone                               x\r\n" );
document.write( "both pipes together                          2\r\n" );
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document.write( "In all cases exactly 1 tank was filled.  Therefore we put 1 for the number\r\n" );
document.write( "of tanks that were filled in all three cases:\r\n" );
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document.write( "                           number of        hours       rate in\r\n" );
document.write( "                         tanks filled    required     tanks/hour     \r\n" );
document.write( "-----------------------------------------------------------------\r\n" );
document.write( "1st pipe alone                1              7\r\n" );
document.write( "2nd pipe alone                1              x\r\n" );
document.write( "both pipes together           1              2\r\n" );
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document.write( "Fill in the three rates in tanks/hour by dividing the number of tanks \r\n" );
document.write( "filled (1) by the hours required:\r\n" );
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document.write( "                           number of        hours       rate in\r\n" );
document.write( "                         tanks filled    required     tanks/hour     \r\n" );
document.write( "-----------------------------------------------------------------\r\n" );
document.write( "1st pipe alone                1              7            1/7\r\n" );
document.write( "2nd pipe alone                1              x            1/x\r\n" );
document.write( "both pipes together           1              2            1/2\r\n" );
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document.write( "The equation comes from\r\n" );
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document.write( "        +   =         \r\n" );
document.write( "  \r\n" );
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document.write( "                   +  = \r\n" );
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document.write( "Solve that and get x = 2.8 hours or 2 hours 48 minutes.\r\n" );
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document.write( "Edwin

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