December 13, 2018 December 13, 2018 08:00 AM PST 09:00 AM PST What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL. December 14, 2018 December 14, 2018 09:00 AM PST 10:00 AM PST 10 Questions will be posted on the forum and we will post a reply in this Topic with a link to each question. There are prizes for the winners.
Author 
Message 
TAGS:

Hide Tags

Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4489

The big outside purple square above has an area of 84
[#permalink]
Show Tags
13 May 2013, 09:53
Question Stats:
77% (02:16) correct 23% (02:30) wrong based on 171 sessions
HideShow timer Statistics
Give yourself a strict time limit of 90 second for this question. Attachment:
square with area 84.JPG [ 22.64 KiB  Viewed 2367 times ]
The big outside purple square above has an area of 84, and the dots are all equal spaced, forming smaller squares. What is the sum of the areas of the shaded yellow regions? (A) 20 (B) 24 (C) 28 (D) 32 (E) 36GMAT students often say, "I could do better on the GMAT Quant if I had unlimited time, but I am always running of time on the hard problems, and I don't know how to do the math faster." Problems such as this, when done via a methodical, long, tedious calculation, can take quite some time, and open up the possibility of numerous calculation errors. When a problem like this appears on the GMAT, there simply has to be some insight method that presents a shortcut to the answer, much easier than the long tedious piecebypiece calculation. See this blog for a detailed discussion of this problemsolving perspective: http://magoosh.com/gmat/2013/howtodo ... thfaster/as well as a complete solution to this particular question. Experts: any tips you would like to add for doing GMAT math faster? Mike
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Mike McGarry Magoosh Test Prep
Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)




VP
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1063
Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8

Re: The big outside purple square above has an area of 84
[#permalink]
Show Tags
13 May 2013, 10:07
We can solve this in 30 sec if we traspose the figures(refer to the image) The area covered is \(\frac{2}{7}\) of the total (2 columns) So area is \(84*\frac{2}{7}=24\)
Attachments
square with area 84.JPG [ 33.21 KiB  Viewed 2263 times ]
_________________
It is beyond a doubt that all our knowledge that begins with experience.
Kant , Critique of Pure Reason Tips and tricks: Inequalities , Mixture  Review: MGMAT workshop Strategy: SmartGMAT v1.0  Questions: Verbal challenge SC III CR New SC set out !! , My QuantRules for Posting in the Verbal Forum  Rules for Posting in the Quant Forum[/size][/color][/b]




Intern
Joined: 05 Apr 2010
Posts: 12

Re: The big outside purple square above has an area of 84
[#permalink]
Show Tags
13 May 2013, 10:02
there are 7X7 squares. Area of each square is 84/49.
Now count the no of squares in yellow. If you face a triangle, try analysing it as a half of rectangle (2square). The total no of squares will be 24. 24 * 84/49 = 24. IMO B.
Took me 01:59.
Any simpler approach?



Manager
Status: *Lost and found*
Joined: 25 Feb 2013
Posts: 121
Location: India
Concentration: General Management, Technology
GPA: 3.5
WE: Web Development (Computer Software)

Re: The big outside purple square above has an area of 84
[#permalink]
Show Tags
13 May 2013, 10:08
Did take lil time to figure out the trick to it! The answer is [B] The trick is to place all the cut sections together and realize that they form a rectangle of 2x*x/ 7 are where x is the side. We already know that x^2 = 84. If we substitute the values we can find that the answer is 24! took me 1:58. I believe this is the shortest way to it Regards, Arpan
_________________
Feed me some KUDOS! *always hungry*
My Thread : Recommendation Letters



Veritas Prep GMAT Instructor
Joined: 11 Dec 2012
Posts: 313

Re: The big outside purple square above has an area of 84
[#permalink]
Show Tags
13 May 2013, 11:03
arpanpatnaik wrote: Did take lil time to figure out the trick to it! The answer is [B] The trick is to place all the cut sections together and realize that they form a rectangle of 2x*x/ 7 are where x is the side. We already know that x^2 = 84. If we substitute the values we can find that the answer is 24! took me 1:58. I believe this is the shortest way to it Regards, Arpan Yeah it might take 30+ seconds just to see the trick of moving the triangles over, it certainly wasn't obvious to me at first. But the shapes of the three figures hint at how the three shapes interconnect, in particular the one block on its own and the triangular shape missing only one square. Once you put them together the yellow portions fill 2 entire columns out of 7, and if you're familiar with the multiplication table you may quickly identify 84 as being 12 x 7, meaning that you have 2/7 of the table filled, with each 1/7 corresponding to exactly 12 units. Ergo, 24. Good question! It took me about a minute just to see the trick and then 15 seconds from there. Sometimes it's good to spend a little time figuring out the correct way instead of diving into calculating the area of irregular shapes. Hope this helps! Ron
_________________
Ron Awad Veritas Prep  GMAT Instructor Save $100 on Veritas Prep GMAT Courses and Admissions Consulting Services Veritas Prep Reviews



MBA Admissions Consultant
Joined: 26 Jan 2013
Posts: 295

Re: The big outside purple square above has an area of 84
[#permalink]
Show Tags
13 May 2013, 11:04
This is easy  with a little experience at pattern recognition! If you put the regions shaded in yellow together  you will be able to fill up two rows of squares  completely. The area of the shaded region, therefore is 2/7th of 84 or 24 units. Cheers!
_________________
Karthik P. Founder and CEO, August Academy.
We are an India based MBA admissions consulting firm. We've been helping Indian MBA applicants (students belonging to the most competitive MBA admissions pool) since 2013. Several of our students study at top 20 schools in the US including Kellogg, MIT, Yale, Ross and Darden, top European schools including London Business School and Oxford, top Canadian schools like Rotman and top Asian schools like ISB and NUS. Our students have won over USD 2.1 Million in scholarships over the last 3 admissions years.
Schedule a free consultation with us.
Click here to view GMATclub verified student testimonials.
Click here to view all our student testimonials.
If you like this post  please give us kudos Thanks much!



NonHuman User
Joined: 09 Sep 2013
Posts: 9138

Re: The big outside purple square above has an area of 84
[#permalink]
Show Tags
21 Jan 2018, 01:18
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: The big outside purple square above has an area of 84 &nbs
[#permalink]
21 Jan 2018, 01:18






