document.write( "Question 1140413: It takes an older pump 4 times as long to drain a certain pool as it does a newer pump. working together, It takes the two pumps 3 hours to drain the pool. How long will it take the newer pump to drain the pool working alone ? \n" ); document.write( "

Algebra.Com's Answer #760928 by ikleyn(52786) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "This problem can be solved in different ways.\r
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document.write( "Let x be the time the faster pump can drain the pool working alone.\r\n" );
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document.write( "Then the time for the slower pump is 4x, according to the condition.\r\n" );
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document.write( "In one hour (in each hour) the faster pump will drain    of the pool volume, while the slower pump will drain   of the pool volume.\r\n" );
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document.write( "Working together, these pumps will drain   of the pool volume per hour.\r\n" );
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document.write( "     =  = .\r\n" );
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document.write( "From the condition,, we know that this sum is equal to    of the tank volume.\r\n" );
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document.write( "Hence,    = ,   which implies   x =  hours =   hours =  hours = 3 hours and 45 minutes.    ANSWER\r\n" );
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\n" ); document.write( "\n" ); document.write( "Another way is THIS :\r
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document.write( "The faster pump works as effectively / (productively) as 4 slower pumps.\r\n" );
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document.write( "Therefore, the problem is equivalent, as if 4+1 = 5 slower pumps work simultaneously.\r\n" );
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document.write( "So, then we know that 5 slower pumps drain the pool in 3 hours.\r\n" );
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document.write( "Hence, one slower pump drains the pool in 3*5 = 15 hours.\r\n" );
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document.write( "The faster pump makes it in 4 times faster, i.e. in  hours = 3 hours and 45 minutes.\r\n" );
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document.write( "You get the same answer.\r\n" );
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