document.write( "Question 123447: Jackie mows a strip of uniform width around her 25m by 15m rectangular lawn and leaves a patch of lawn that is 60% of the original area. What is the width of the strip? \n" ); document.write( "
Algebra.Com's Answer #90601 by ankor@dixie-net.com(22740)\"\" \"About 
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Jackie mows a strip of uniform width around her 25 m by 15m rectangular lawn and leaves a patch of lawn that is 60% of the original area. What is the width of the strip?
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\n" ); document.write( "Draw this as one rectangle inside another rectangle. Label the large rectangle
\n" ); document.write( "as 25 by 15. Label the width of the strip between the rectangle as x. I will be
\n" ); document.write( "apparent that the dimension of the inner rectangle will be (25-2x) by (15-2x)
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\n" ); document.write( "Find the area of whole lawn: 25 * 15 = 375 sq/m
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\n" ); document.write( "It said the inner area was 60% of the whole lawn: .6 * 375 = 225 sq/m
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\n" ); document.write( "An equation of the inner area would be:
\n" ); document.write( "(25-2x)*(15-2x) = 225
\n" ); document.write( "FOIL
\n" ); document.write( "375 - 50x - 30x + 4x^2 = 225
\n" ); document.write( "Arrange as a quadratic equation:
\n" ); document.write( "4x^2 - 80x + 375 - 225 = 0
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\n" ); document.write( "4x^2 - 80x + 150 = 0
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\n" ); document.write( "Use the quadratic equation to solve this: a=4; b=-80; c=150
\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( "\"x+=+%28-%28-80%29+%2B-+sqrt%28-80%5E2+-+4+%2A+4+%2A+150+%29%29%2F%282%2A4%29+\"
\n" ); document.write( ":
\n" ); document.write( "\"x+=+%2880+%2B-+sqrt%286400+-+2400+%29%29%2F%288%29+\"
\n" ); document.write( "\"x+=+%2880+%2B-+sqrt%284000%29%29%2F%288%29+\"
\n" ); document.write( "Find the square root of 4000
\n" ); document.write( "Two solutions
\n" ); document.write( "\"x+=+%2880+%2B+63.246%29%2F%288%29+\"
\n" ); document.write( "\"x+=+143.246%2F8\"
\n" ); document.write( "x = 17.9
\n" ); document.write( "and
\n" ); document.write( "\"x+=+%2880+-+63.246%29%2F%288%29+\"
\n" ); document.write( "\"x+=+16.754%2F8\"
\n" ); document.write( "x = 2.1, this the solution that makes sense
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\n" ); document.write( "The width of the mown strip is 2.1 meters
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\n" ); document.write( "Check solution by finding the area of the inner portion
\n" ); document.write( "2x = 2*2.1 = 4.2
\n" ); document.write( "(25-4.2) * 15-4.2) =
\n" ); document.write( "20.8 * 10.8 = 224.64 ~ 225 which is 60% of 375 \n" ); document.write( "
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