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# How many rectangles are found in the lattice below?

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 8005
GMAT 1: 760 Q51 V42
GPA: 3.82
How many rectangles are found in the lattice below?  [#permalink]

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09 Apr 2019, 00:11
00:00

Difficulty:

55% (hard)

Question Stats:

55% (01:35) correct 45% (01:56) wrong based on 38 sessions

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[GMAT math practice question]

How many rectangles are found in the lattice below?

Attachment:

4.9.png [ 1.72 KiB | Viewed 665 times ]

A. 90
B. 100
C. 120
D. 150
E. 180

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MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
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"Only $79 for 1 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" ##### Most Helpful Expert Reply Math Expert Joined: 02 Aug 2009 Posts: 7958 Re: How many rectangles are found in the lattice below? [#permalink] ### Show Tags 09 Apr 2019, 08:23 4 2 MathRevolution wrote: [GMAT math practice question] How many rectangles are found in the lattice below? Attachment: 4.9.png A. 90 B. 100 C. 120 D. 150 E. 180 The question basically asks to choose two lines from 5 rows and 2 lines from 6 columns, so 5C2*6C2=$$\frac{5*4}{2}*\frac{6*5}{2}=5*2*3*5=150$$ D _________________ ##### General Discussion Director Joined: 28 Jul 2016 Posts: 597 Location: India Concentration: Finance, Human Resources GPA: 3.97 WE: Project Management (Investment Banking) Re: How many rectangles are found in the lattice below? [#permalink] ### Show Tags 09 Apr 2019, 21:17 2 The length has 6 lines and width has 5 lines to make a rectangle take any 2 lines from width and other 2 lines from length hence 6c2 and 5c2 thus 6c2*5C2 =150 thus D Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 8005 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: How many rectangles are found in the lattice below? [#permalink] ### Show Tags 11 Apr 2019, 01:47 => Each rectangle is uniquely determined by the intersections between two vertical lines and two horizontal lines. Since we have 6 vertical lines and 5 horizontal lines, the number of rectangles is 6C2*5C2 = 15*10 = 150. Therefore, D is the answer. Answer: D _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$79 for 1 month Online Course"
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Joined: 17 May 2018
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Re: How many rectangles are found in the lattice below?  [#permalink]

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11 Apr 2019, 02:01
Are we also taking square into accounts?
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 8005
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: How many rectangles are found in the lattice below?  [#permalink]

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12 Apr 2019, 11:24
heisenberg11 wrote:
Are we also taking square into accounts?

A squares are a rectangle, actually.
However, it doesn't matter for this question.

Happy Studying !!!
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MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
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Re: How many rectangles are found in the lattice below?  [#permalink]

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13 Apr 2019, 04:17
heisenberg11 wrote:
Are we also taking square into accounts?

Yes, we are taking squares too into account since squares are also rectangles..
I can say..
Squares are rectangles. Rectangles are parallelogram and parallelogram are quadrilateral.
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Re: How many rectangles are found in the lattice below?   [#permalink] 13 Apr 2019, 04:17
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