document.write( "Question 1185242: A cistern can be filled by two pipes. The small pipe alone will take 24 minutes
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document.write( "longer than the larger pipe to fill the cistern alone. The small pipe alone will take
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document.write( "32 minutes longer to fill the cistern alone than when the two pipes are operating
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document.write( "together. How long will it take the larger pipe to fill the cistern alone. \n" );
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Algebra.Com's Answer #816072 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! A cistern can be filled by two pipes. \n" ); document.write( " let x = time required by the larger pipe alone \n" ); document.write( ": \n" ); document.write( " The small pipe alone will take 24 minutes longer than the larger pipe to fill the cistern alone. \n" ); document.write( " (x+24) = time required by the smaller pipe \n" ); document.write( ": \n" ); document.write( " The small pipe alone will take 32 minutes longer to fill the cistern alone than when the two pipes are operating together. \n" ); document.write( "let t = time required when working together \n" ); document.write( "then \n" ); document.write( "t + 32 = x+24 \n" ); document.write( "t = x + 24 - 32 \n" ); document.write( "t = x - 8, time required when working together \n" ); document.write( ": \n" ); document.write( "Let the full cistern = 1 \n" ); document.write( " \n" ); document.write( "multiply by x(x+24) \n" ); document.write( "(x+24)(x-8) + x(x-8) = x(x+24) \n" ); document.write( "x^2 - 8x + 24x - 192 + x^2 - 8x = x^2 + 24x \n" ); document.write( "Combine like terms on the left \n" ); document.write( "x^2 + x^2 - x^2 - 8x + 24x - 8x - 24x - 192 = 0 \n" ); document.write( "x^2 - 16x - 192 = 0 \n" ); document.write( "a quadratic equation which we can factor \n" ); document.write( "(x-24)(x+8) = 0 \n" ); document.write( "positive solution \n" ); document.write( "x = 24 min, large pipe working alone \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check solution \n" ); document.write( "small pipe alone: 24 + 24 = 48 min \n" ); document.write( "working together: 24 - 8 = 16 min \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |