document.write( "Question 134620: An inlet pipe can fill a tank in 6 minutes. A drain can empty the tank in 8 minutes. If the tank is empty and both the pipe and drain are open, how long will it take before the tank over flows? \n" ); document.write( "
Algebra.Com's Answer #98492 by vleith(2983)\"\" \"About 
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Think about what happens in the time it takes to 'fill the tank'. With the drain open, 6/8th of the water will drain in the time it would take to fill the tank with the drain closed.\r
\n" ); document.write( "\n" ); document.write( "So instead of having a full tank, we have a a tank that is (1 - 3/4) full = 1/4 full.\r
\n" ); document.write( "\n" ); document.write( "So the tank fills 1/4 of the way every 6 minutes. \r
\n" ); document.write( "\n" ); document.write( "How many minutes to fill it at that rate?? We will need to add in 1/4 + 1/4 + 1/4 + 1/4 = 1 \r
\n" ); document.write( "\n" ); document.write( "We need 4 times the 6 minutes to fill the tank. ==> 24 minutes\r
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\n" ); document.write( "\n" ); document.write( "Look at it another way, You could fill the tank 4 times in 24 minutes if the drain was closed. You could drain the tank 3 times in 24 minutes if you had 3 full tanks ready to rock and roll.\r
\n" ); document.write( "\n" ); document.write( "Net 4 - 3 = 1 tank after 24 minutes.\r
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