document.write( "Question 1183385: Hello\r
\n" ); document.write( "\n" ); document.write( "A pipe can empty a tank in 40 minutes.
\n" ); document.write( "A second pipe with diameter twice as much as
\n" ); document.write( " that of the first is also attached with the tank to empty it.\r
\n" ); document.write( "\n" ); document.write( "The two pipes together can empty the tank in 8
\n" ); document.write( "minutes.\r
\n" ); document.write( "\n" ); document.write( "I don't understand how they got 8?\r
\n" ); document.write( "\n" ); document.write( "How would I go about solving this?\r
\n" ); document.write( "\n" ); document.write( "Thanks in advance,\r
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Algebra.Com's Answer #813671 by math_helper(2461) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "The first pipe has cross-sectional area  \r
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document.write( "The 2nd pipe has cross-sectional area  \r
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document.write( "But you are told  so \r
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document.write( "Thus, the 2nd pipe can empty 4 times faster.\r
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document.write( "The first pipe empties 1/40 tank per minute.
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document.write( "Therefore, the 2nd pipe empties 4(1/40) = 1/10 tank per minute.\r
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document.write( "Working together:  1/40 + 1/10 = 1/40 + 4/40 = 5/40 = 1/8 tank per minute (or, equivalently, they take 8min to empty the entire tank when working together). \n" );
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