document.write( "Question 203502This question is from textbook Elementary & Intermediate Algebra
\n" ); document.write( ": Please help with word problem: \r
\n" ); document.write( "\n" ); document.write( "Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and an empty tank can be filled in 45 minutes with the inlet pipe opened. If both pipes are accidentally opened when the tank is full, then how long will it take to empty the tank? \n" ); document.write( "

Algebra.Com's Answer #852450 by ikleyn(52957) $\"\"$ $\"About$

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\n" ); document.write( "A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes
\n" ); document.write( "if the drain is opened and an empty tank can be filled in 45 minutes with the inlet pipe opened.
\n" ); document.write( "If both pipes are accidentally opened when the tank is full, then how long will it take to empty the tank?
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\n" ); document.write( "\n" ); document.write( "        The solution by @Theo, giving the answer 18 minutes to empty the tank \r
\n" ); document.write( "\n" ); document.write( "        is   (a) incorrect and   (b) contradicts to common sense.\r
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\n" ); document.write( "\n" ); document.write( "        I will give here short, clear and correct solution.\r
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document.write( "The drain opening removes  water from the tank at the rate of    of the tank volume per minute.\r\n" );
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document.write( "The inlet pipe adds water top the tank at the rate of    of the tank volume per minute.\r\n" );
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document.write( "The combined rate when both drain and inlet pipe works simultaneously is the difference\r\n" );
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document.write( "     -  = use the common denominator 90 =  -  = .\r\n" );
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document.write( "In other words, when the full tank remained with both the drain and the inlet opened,\r\n" );
document.write( "then    of the tank volume is removed each minute from the tank.\r\n" );
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document.write( "From it, we conclude that the time to empty the tank is  90 minutes,  or 1 hour and 30 minutes.    <<<---===  ANSWER\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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\n" ); document.write( "\n" ); document.write( "Since the @Theo' solution is incorrect, ignore his post for the peace in your mind.\r
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\n" ); document.write( "\n" ); document.write( "His error is that he uses the sum of rates of works as an effective/combined rate,
\n" ); document.write( "while in this problem the difference of rates should be used.\r
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\n" ); document.write( "\n" ); document.write( "It is a typical error for those who write wordy: when a person writes wordy, it opens the space for many errors.\r
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\n" ); document.write( "\n" ); document.write( "Use my solution, instead. It is short, clear and instructive.\r
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