document.write( "Question 409722: One pipe can fill a swimming pool in 6 hours, and another pipe can do it in 9 hr. How long will it take the two pipes working together to fill the pool 3/4 full? \n" ); document.write( "

Algebra.Com's Answer #288314 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"t\"$ = time for both pipes to fill 3/4 of the pool
\n" ); document.write( "given:
\n" ); document.write( " $\"R%5B1%5D+=+1%2F6\"$ 1 pool/6 hours
\n" ); document.write( " $\"R%5B2%5D+=+1%2F9\"$ 1 pool/9 hours
\n" ); document.write( "---------------------
\n" ); document.write( " $\"R%5B1%5D+%2B+R%5B2%5D+=+%283%2F4%29%2Ft\"$
\n" ); document.write( " $\"1%2F6+%2B+1%2F9+=+%283%2F4%29%2Ft\"$
\n" ); document.write( "Multiply both sides by $\"18t\"$
\n" ); document.write( " $\"3t+%2B+2t+=+%283%2A18%29%2F4\"$
\n" ); document.write( " $\"5t+=+27%2F2\"$
\n" ); document.write( " $\"t+=+2.7\"$ hr
\n" ); document.write( "The 2 pipes together take 2.7 hr, or 2 hrs and 42 min
\n" ); document.write( "to fill 3/4 of the pool
\n" ); document.write( " \n" ); document.write( "

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