document.write( "Question 854115: A pool can be filled by one pipe in 20 hours and by a second pipe 60 hours. How long will it take using both pipes to fill the pool? explain Please \n" ); document.write( "

Algebra.Com's Answer #514440 by josmiceli(19441) $\"\"$ $\"About$

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The rate of filling of the 1st pipe is:
\n" ); document.write( "( 1 pool filled ) / ( 20 hrs )
\n" ); document.write( "The rate of filling of the 2nd pipe is:
\n" ); document.write( "( 1 pool filled ) / ( 60 hrs )
\n" ); document.write( "-------------------------------
\n" ); document.write( "Let $\"+t+\"$ = the time in hours for the pipes
\n" ); document.write( "to fill the pool together. the rate of both filling is:
\n" ); document.write( "( 1 pool filled ) / ( t hrs )
\n" ); document.write( "----------------------
\n" ); document.write( "To get the rate of filling of both pipes
\n" ); document.write( "together, add their rates of filling:
\n" ); document.write( " $\"+1%2F20+%2B+1%2F60+=+1%2Ft+\"$
\n" ); document.write( "Multiply both sides by $\"+60t+\"$
\n" ); document.write( " $\"+3t+%2B+t+=+60+\"$
\n" ); document.write( " $\"+4t+=+60+\"$
\n" ); document.write( " $\"+t+=+15+\"$
\n" ); document.write( "--------------
\n" ); document.write( "With both pipes filling together, the
\n" ); document.write( "pool is filled in 15 hrs\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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