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The figure shows a square patio surrounded by a walkway of [#permalink]
 24 Oct 2008, 03:46
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The figure shows a square patio surrounded by a walkway of width x meters. If the area of the walkway is 132 square meters and the width of the patio is 5 meters greater than the width of the walkway, what is the area of the patio, in square meters? A. 56 B. 64 C. 68 D. 81 E. 100
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Re: PS : SQUARE PATIO [#permalink]
24 Oct 2008, 05:16
B
(5+3x)^2 - (5+x)^2 = 132
2x(10+4x) = 132
x(5+2x) = 33 = 3*11
So, x can be 3 and not 11
8^2 = 64
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Re: PS : SQUARE PATIO [#permalink]
24 Oct 2008, 06:33
LiveStronger wrote: B
(5+3x)^2 - (5+x)^2 = 132
2x(10+4x) = 132
x(5+2x) = 33 = 3*11
So, x can be 3 and not 11
8^2 = 64 nice one  especially this step ---- x(5+2x) = 33 = 3*11 I was wondering how to reduce the calculation thanks
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Re: PS : SQUARE PATIO [#permalink]
24 Oct 2008, 09:55
So, x can be 3 and not 11 Why not 11? (I did this the ultra long way) amitdgr wrote: LiveStronger wrote: B
(5+3x)^2 - (5+x)^2 = 132
2x(10+4x) = 132
x(5+2x) = 33 = 3*11
So, x can be 3 and not 11
8^2 = 64 nice one especially this step ---- x(5+2x) = 33 = 3*11 I was wondering how to reduce the calculation thanks |
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Re: PS : SQUARE PATIO [#permalink]
24 Oct 2008, 10:07
bigfernhead wrote: So, x can be 3 and not 11 Why not 11? (I did this the ultra long way) amitdgr wrote: LiveStronger wrote: B
(5+3x)^2 - (5+x)^2 = 132
2x(10+4x) = 132
x(5+2x) = 33 = 3*11
So, x can be 3 and not 11
8^2 = 64 nice one especially this step ---- x(5+2x) = 33 = 3*11 I was wondering how to reduce the calculation thanks x > 0 so 5+3x > x x(5+2x) = 3*11 x has to be the smaller value and (5+2x) the larger. so x = 3 even I did it the ULTRA lonnggg wayy
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Re: PS : SQUARE PATIO [#permalink]
29 Dec 2008, 15:47
I am confused - if the patio is surounded by the walkway- how is the width of the patio greater than the width of the walkway???
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 02:46
LiveStronger wrote: B
(5+3x)^2 - (5+x)^2 = 132
2x(10+4x) = 132
x(5+2x) = 33 = 3*11
So, x can be 3 and not 11
8^2 = 64 can someone please explain this step how did we get this (5+3x)^2 - (5+x)^2 = 132
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 08:27
gurpreet07 wrote: LiveStronger wrote: B
(5+3x)^2 - (5+x)^2 = 132
2x(10+4x) = 132
x(5+2x) = 33 = 3*11
So, x can be 3 and not 11
8^2 = 64 can someone please explain this step how did we get this (5+3x)^2 - (5+x)^2 = 132 Width of the patio is 5m greater than the width of the walkway. So, width of the Patio = 5+x (since x is the width of the walkway) To get the area of the walkway, we need to substract the area of the bigger square minus the patio. Area of patio = (5+x)^2 Side of the bigger aquare = x+x+5+x = 5+3x So, area of the bigger square is = (5+3x)^2 Hence, (5+3x)^2 - (5+x)^2 = 132
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 10:17
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Hi LiveStronger,
nice way to solve it. could you please explain me how do you go from step 1 to step 2. It took me 3 lines of operations and you can do it in just one. I definitely need to be faster in the exam so this kind of tips will be really useful.
thks!!
Step 1. (5+3x)^2 - (5+x)^2 = 132
Step 2. 22x(10+4x) = 132
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 10:38
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marcap wrote: Hi LiveStronger,
nice way to solve it. could you please explain me how do you go from step 1 to step 2. It took me 3 lines of operations and you can do it in just one. I definitely need to be faster in the exam so this kind of tips will be really useful.
thks!!
Step 1. (5+3x)^2 - (5+x)^2 = 132
Step 2. 22x(10+4x) = 132 I used a^2 - b^2 = (a+b)(a-b) formula
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 11:35
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The solutions above subtract the inner square from the outer one, which is a good approach. One other way to get to the same answer: divide up the patio. You have the four corners, measuring x by x, and four rectangles lined up with each side of the inner square which measure x by x+5. So: 4x^2 + 4x(x+5) = 132 2x^2 + 5x = 33 etc.
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 12:13
amitdgr wrote: The figure shows a square patio surrounded by a walkway of width x meters. If the area of the walkway is 132 square meters and the width of the patio is 5 meters greater than the width of the walkway, what is the area of the patio, in square meters?
A. 56
B. 64
C. 68
D. 81
E. 100 width of the walkway = x width of the patio = x+5 = x+5 width of the whole area = x+5+x = 3x+5 (3x+5)^2 - (x+5)^2 = 132 9x^2 + 30x + 25 - x^2 -10x -25 = 132 8x^2 + 20x = 132 4 (2x^2 + 5x) = 132 2x^2 + 5x - 33 = 0 2x^2 + 11x - 6x - 33 = 0 x (2x+11) -3 (3x +11) = 0 (x-3) (2x+11) = 0 x = 3 or -11/2 but -11/2 is not possible as length/width cannot be in -ve. so x = 30 so area of the patio = (3+5)^2 = 64
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 21:52
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Thanks GMAT TIGER and LiveStronger for d explanation......
Actually i go numb when i see numbers.......
can u please suggest me how should i improve my quant
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Re: PS : SQUARE PATIO [#permalink]
30 Dec 2008, 23:38
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If its convenient, u can also attempt backsolving it:-
On first glance A,C are clearly out.
(E) 100 means side of patio is 10 so width of walkway =5. the walkway has 4 rectangles 2 among them are each 20*5=100 --impossible for total of 132.
(D) 81 means side of patio is 9 so width of walkway =4. the walkway has 4 rectangles 2 among them are each 17*4=68. 2 such rectangles account for 136--hence impossible for total of 132.
(C) 64 means side of patio is 8 so width of walkway =3. the walkway has 4 rectangles 2 among them are each 14*3=42 and rest are 8*24.total= 2(42+24)=132.
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Re: PS : SQUARE PATIO [#permalink]
25 Aug 2011, 23:22
amitdgr wrote: The figure shows a square patio surrounded by a walkway of width x meters. If the area of the walkway is 132 square meters and the width of the patio is 5 meters greater than the width of the walkway, what is the area of the patio, in square meters?
A. 56
B. 64
C. 68
D. 81
E. 100 Smaller square=Patio Let the side of Patio be "s". Width of walkway=x width of the patio is 5 meters greater than the width of the walkway(Actually it should be "side of the patio is 5 meters greater than the width of the walkway" because patio is a square) So, s=x+5If we see the figure properly, the outer quadrilateral is also a square with side s+x+x OR x+5+x+x=3x+5We know, the area of the walkway is 132 square meters: Area of walkway=Area of outer square-Area of inner square Area of walkway=(3x+5)^2-(x+5)^2=132 (3x+5)^2-(x+5)^2=132(3x)^2+(5)^2+2*3x*5-(x^2+5^2+2*5x)=1329x^2+25+30x-x^2-25-10x=1329x^2+30x-x^2-10x=1328x^2+20x=1322x^2+5x=332x^2+5x-33=02x^2+11x-6x-33=0x(2x+11)-3(2x+11)=0(x-3)(2x+11)=0x=3 \hspace{3} OR \hspace{3} x=-\frac{11}{2}Width can't be -ve. So, x=3s=x+5=3+5=8Area of the patio =s^2=8^2=64Ans: "B"
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Re: PS : SQUARE PATIO
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25 Aug 2011, 23:22
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