document.write( "Question 1207781: A bathroom tub will fill in 15 minutes with both faucets open and the stopper in place. With both faucets closed and the stopper removed, the tub will empty in 20 minutes. How long will it take for the tub to fill if both faucets are open and the stopper is removed?\r
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\n" ); document.write( "\n" ); document.write( "My equation is this:\r
\n" ); document.write( "\n" ); document.write( "(x/15) + (x/20) = 1\r
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Algebra.Com's Answer #845863 by ikleyn(52781) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "A bathroom tub will fill in 15 minutes with both faucets open and the stopper in place.
\n" ); document.write( "With both faucets closed and the stopper removed, the tub will empty in 20 minutes.
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\n" ); document.write( "\n" ); document.write( "Your equation is incorrect.\r
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document.write( "In this problem, there are two opposite processes.\r\n" );
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document.write( "One process is filling with the rate of    of the volume per minute\r\n" );
document.write( "(two faucets combined).\r\n" );
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document.write( "Another process is draining with the rate    of the volume per minute.\r\n" );
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document.write( "So, when both facets are open and the stopper is removed, the net filling rate is the difference \r\n" );
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document.write( "     -  =  -  =   of the volume per minute.\r\n" );
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document.write( "It means that the filling process will take 60 minutes, or 1 hour.    ANSWER\r\n" );
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\n" ); document.write( "\n" ); document.write( "Thus, the problem is just solved (mentally).\r
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\n" ); document.write( "\n" ); document.write( "If you want to write an equation, you should formalize this reasoning.\r
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document.write( "Let \"t\" be the time to fill, in minutes.\r\n" );
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document.write( "Then in t minutes, the two facets will fill    part of the volume,\r\n" );
document.write( "while through the stopper hole, the   part of the volume will be removed.\r\n" );
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document.write( "The volume will be fully filled when\r\n" );
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document.write( "     -  = 1   (the whole volume).\r\n" );
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document.write( "Write with common denominator and find t\r\n" );
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document.write( "     -  = 1,\r\n" );
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document.write( "     = 1,\r\n" );
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document.write( "    t = 60*1 = 60 minutes.\r\n" );
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document.write( "ANSWER.  The required time is 60 minutes,  or 1 hour.\r\n" );
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\n" ); document.write( "\n" ); document.write( "To see many other similar (and different) introductory problems on joint work,
\n" ); document.write( "solved with complete explanations to teach you, look into the lessons\r
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\n" ); document.write( "\n" ); document.write( " - Using Fractions to solve word problems on joint work \r
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\n" ); document.write( "\n" ); document.write( "Read it and get be trained in solving joint-work problems.\r
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\n" ); document.write( "\n" ); document.write( "Consider this lesson as your textbook, handbook, guidebook, tutorials and (free of charge) home teacher,
\n" ); document.write( "which is always with you to help and to inspire.\r
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