document.write( "Question 513152: A tank can be filled by a hose in 15 hours. It can be emptied by a drainpipe in 25 hours. If the drainpipe is open while the tank is being filled, how long does it take to fill the tank? \n" ); document.write( "

Algebra.Com's Answer #342888 by stanbon(75887) $\"\"$ $\"About$

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A tank can be filled by a hose in 15 hours. It can be emptied by a drainpipe in 25 hours. If the drainpipe is open while the tank is being filled, how long does it take to fill the tank?
\n" ); document.write( "----------
\n" ); document.write( "Fill rate: 1/15 job/hr
\n" ); document.write( "-----
\n" ); document.write( "Drain rate: 1/25 job/hr
\n" ); document.write( "--------------------------
\n" ); document.write( "Together rate: 1/x job/hr
\n" ); document.write( "----------------------------
\n" ); document.write( "Equation:
\n" ); document.write( "rate - rate = rate
\n" ); document.write( "1/15 - 1/25 = 1/x
\n" ); document.write( "---
\n" ); document.write( "Multiply thru by 75x to get:
\n" ); document.write( "5x - 3x = 75
\n" ); document.write( "2x = 75
\n" ); document.write( "x = 37.5 hrs (time to fill the tank together)
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\n" ); document.write( "Cheers,
\n" ); document.write( "stan H.
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