document.write( "Question 938939: Pipe A fills the pool in 8 hours, pipe B fills the pool in 12 hours. If pipe A runs for 90 minutes, then pipe B is turned on , how long will it take to fill the pool?
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Algebra.Com's Answer #573263 by macston(5194) $\"\"$ $\"About$

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Pipe A fills $\"1%2F8\"$ pool per hour. $\"1%2F8\"$ *100%=12.5% per hour
\n" ); document.write( "Pipe B fills $\"1%2F12\"$ pool per hour. $\"1%2712\"$ *100%=8.3% per hour
\n" ); document.write( "Convert the 90 minute fill time to hours:
\n" ); document.write( " $\"90+minutes%2F%2860+minutes%2Fhr%29\"$ =1.5 hour
\n" ); document.write( "Pipe A fills 12.5% of pool/hr x 1.5 hours=18.75% of pool
\n" ); document.write( "Together Pipes A and B fill (12.5%+8.3%)=20.8% of the pool per hour.
\n" ); document.write( "After 1.5 hours of just Pipe A, 100%-18.75%=81.25% is left to fill.
\n" ); document.write( "81.25% of the pool/20.8% per hour (both Pipes)=3.9 hours to finish filling.
\n" ); document.write( "1.5 hours(just Pipe A) + 3.9 hours(both Pipes)=5.4 hours total to fill pool. \n" ); document.write( "

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