document.write( "Question 572862: One pump can drain a pool in 11 minutes. When a second pump is also used, the pool only takes 8 minutes to drain. How long would it take the second pump to drain the pool if it were the only pump in use? \n" ); document.write( "

Algebra.Com's Answer #368556 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+t+\"$ = time in minutes for 2nd pump alone to drain pool
\n" ); document.write( "Add the rates of pumping of each pump to get
\n" ); document.write( "the rate of both pumping together
\n" ); document.write( "Rate of 1st pump:
\n" ); document.write( " $\"+1%2F11+\"$ ( 1 pool drained/ 11 min )
\n" ); document.write( "Rate of 2nd pump:
\n" ); document.write( " $\"+1%2Ft+\"$ ( 1 pool drained / t min )
\n" ); document.write( "---------------------------
\n" ); document.write( " $\"+1%2F11+%2B+1%2Ft+=+1%2F8+\"$
\n" ); document.write( "Multiply both sides by $\"+88t+\"$
\n" ); document.write( " $\"+8t+%2B+88+=+11t+\"$
\n" ); document.write( " $\"+3t+=+88+\"$
\n" ); document.write( " $\"+t+=+29.333+\"$
\n" ); document.write( " $\"+.333%2A60+=+20+\"$
\n" ); document.write( "the 2nd pump takes 29 min and 20 sec to drain pool by itself
\n" ); document.write( "check answer:
\n" ); document.write( " $\"+1%2F11+%2B+1%2F29.333+=+1%2F8+\"$
\n" ); document.write( " $\"+.09091+%2B+.034091+=+.125+\"$
\n" ); document.write( " $\"+.125001+=+.125+\"$
\n" ); document.write( "error due to rounding off \n" ); document.write( "

\n" );