GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 18 Dec 2018, 11:40

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

## Events & Promotions

###### Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### Happy Christmas 20% Sale! Math Revolution All-In-One Products!

December 20, 2018

December 20, 2018

10:00 PM PST

11:00 PM PST

This is the most inexpensive and attractive price in the market. Get the course now!
• ### Key Strategies to Master GMAT SC

December 22, 2018

December 22, 2018

07:00 AM PST

09:00 AM PST

Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

# Planning is in progress for a fenced, rectangular playground with an a

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51280
Planning is in progress for a fenced, rectangular playground with an a  [#permalink]

### Show Tags

30 Jul 2018, 21:07
16
00:00

Difficulty:

15% (low)

Question Stats:

77% (01:09) correct 23% (02:18) wrong based on 458 sessions

### HideShow timer Statistics

Planning is in progress for a fenced, rectangular playground with an area of 1,600 square meters. The graph above shows the perimeter, in meters, as a function of the length of the playground. The length of the playground should be how many meters to minimize the perimeter and, therefore, the amount of fencing needed to enclose the playground?

A. 10
B. 40
C. 60
D. 160
E. 340

NEW question from GMAT® Quantitative Review 2019

(PS14060)

Attachment:

shot28.jpg [ 14.9 KiB | Viewed 3035 times ]

_________________
Intern
Joined: 11 Jul 2018
Posts: 20
Re: Planning is in progress for a fenced, rectangular playground with an a  [#permalink]

### Show Tags

30 Jul 2018, 22:03
1
Lowest point on the graph is 40, 160
i.e. Length = 40 and Perimeter = 160

This is lowest for both Length as well as perimeter.

But this looks like a trick question and may have some hidden meaning
Senior Manager
Joined: 18 Jun 2018
Posts: 255
Planning is in progress for a fenced, rectangular playground with an a  [#permalink]

### Show Tags

30 Jul 2018, 22:13
1
2
Bunuel wrote:

Planning is in progress for a fenced, rectangular playground with an area of 1,600 square meters. The graph above shows the perimeter, in meters, as a function of the length of the playground. The length of the playground should be how many meters to minimize the perimeter and, therefore, the amount of fencing needed to enclose the playground?

A. 10
B. 40
C. 60
D. 160
E. 340

NEW question from GMAT® Quantitative Review 2019

(PS14060)

Attachment:
shot28.jpg

OA:B
Lowest point on the graph(40,160) where 40 is the length and 160 is perimeter.
So length should be 40
This matches with
Quote:
Among all rectangles of given area, the square has the least perimeter.

Given Area = $$1600 m^2$$
For perimeter to be least, it should be square with side a.
$$a^2=1600m^2$$
$$a=40 m$$
$$Perimeter =4a =4*40 =160 m$$
Intern
Joined: 03 Sep 2017
Posts: 12
Re: Planning is in progress for a fenced, rectangular playground with an a  [#permalink]

### Show Tags

31 Jul 2018, 02:21
Answer is B. The graph seems a distraction as you can backsolve to get an answer. Also Square has the least perimeter when it comes to Polygons so B jumps out at you
Intern
Joined: 20 Jul 2017
Posts: 1
Re: Planning is in progress for a fenced, rectangular playground with an a  [#permalink]

### Show Tags

14 Aug 2018, 22:32
bangu wrote:
Lowest point on the graph is 40, 160
i.e. Length = 40 and Perimeter = 160

This is lowest for both Length as well as perimeter.

But this looks like a trick question and may have some hidden meaning

To minimize perimeter i.e the rectangle must become a square
Therefore a^2=1600 . =>a=40
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13108
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Planning is in progress for a fenced, rectangular playground with an a  [#permalink]

### Show Tags

Updated on: 16 Nov 2018, 13:54
Hi All,

While this prompt is wordy, the relevant facts are not too hard to pull out. We're told that a rectangular playground will have an area of 1,600 square meters and we want to MINIMIZE the perimeter of the playground. We're asked for the LENGTH of the playground under those circumstances.

This question is based on a relatively rare Geometry rule. When given a 'fixed' area, the smallest perimeter of a rectangle that will have that exact area will occur when the shape is actually a SQUARE. You can actually prove this with a bit of experimentation:

A 1 meter x 1600 meter rectangle would have a perimeter of 3202 meters
A 2 meter x 800 meter rectangle would have a perimeter of 1604 meters
A 4 meter x 400 meter rectangle would have a perimeter of 808 meters
....
Etc.
A 40 meter x 40 meter rectangle would have a perimeter of 1600 meters

With an area of 1600 square meters, the square would have dimensions of 40 meters x 40 meters --> meaning that the 'length' would be 40.

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/ *****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***** Originally posted by EMPOWERgmatRichC on 15 Nov 2018, 22:20. Last edited by EMPOWERgmatRichC on 16 Nov 2018, 13:54, edited 1 time in total. SVP Joined: 26 Mar 2013 Posts: 1920 Re: Planning is in progress for a fenced, rectangular playground with an a [#permalink] ### Show Tags 16 Nov 2018, 04:19 EMPOWERgmatRichC wrote: Hi All, While this prompt is wordy, the relevant facts are not too hard to pull out. We're told that a rectangular playground will have an area of 1,600 square meters and we want to MINIMIZE the perimeter of the playground. We're asked for the LENGTH of the playground under those circumstances. This question is based on a relatively rare Geometry rule. When given a 'fixed' area, the smallest perimeter of a rectangle that will have that exact area will occur when the shape is actually a SQUARE. You can actually prove this with a bit of experimentation: A 1 meter x 1600 meter rectangle would have a perimeter of 3202 meters A 2 meter x 800 meter rectangle would have a perimeter of 1604 meters A 4 meter x 400 meter rectangle would have a perimeter of 808 meters .... Etc. A 40 meter x400 meter rectangle would have a perimeter of 160 meters With an area of 1600 square meters, the square would have dimensions of 40 meters x 40 meters --> meaning that the 'length' would be 40. Final Answer: GMAT assassins aren't born, they're made, Rich Hi EMPOWERgmatRichC I thin there is a small typo highlighted. It must be 40. Also, I have a question. Why did not you use the graph attached with the question? is something tricky or wrong? Thanks in advance CEO Joined: 11 Sep 2015 Posts: 3243 Location: Canada Re: Planning is in progress for a fenced, rectangular playground with an a [#permalink] ### Show Tags 16 Nov 2018, 07:03 Top Contributor Bunuel wrote: Planning is in progress for a fenced, rectangular playground with an area of 1,600 square meters. The graph above shows the perimeter, in meters, as a function of the length of the playground. The length of the playground should be how many meters to minimize the perimeter and, therefore, the amount of fencing needed to enclose the playground? A. 10 B. 40 C. 60 D. 160 E. 340 Attachment: shot28.jpg It's a good idea to first try to understand what the graph is telling us. For example, the leftmost point on the curve has the coordinates (10, 340) This tells us that, if the length of the playground is 10 meters, then a total of 340 meters of fencing is required. This makes sense, since we want the playground to have an area of 1600 square meters. So, if the length of the rectangular playground is 10 meters, the width must be 160 meters (since this will give us an area of 1600) If the length and width are 10 and 160, then the perimeter = 10 + 10 + 160 + 160 = 340 Our goal is to MINIMIZE the perimeter. So, when we examine the points on the curve, we must find the point with the smallest y-coordinate, since the y-coordinate represents the perimeter of the fence. We can see the perimeter is minimized at the point (40, 160). This point tells us that, when the playground has length 40 meters, the perimeter is a mere 160 meters. Answer: B Cheers, Brent _________________ Test confidently with gmatprepnow.com EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 13108 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: Planning is in progress for a fenced, rectangular playground with an a [#permalink] ### Show Tags 16 Nov 2018, 13:57 Mo2men wrote: EMPOWERgmatRichC wrote: Hi All, While this prompt is wordy, the relevant facts are not too hard to pull out. We're told that a rectangular playground will have an area of 1,600 square meters and we want to MINIMIZE the perimeter of the playground. We're asked for the LENGTH of the playground under those circumstances. This question is based on a relatively rare Geometry rule. When given a 'fixed' area, the smallest perimeter of a rectangle that will have that exact area will occur when the shape is actually a SQUARE. You can actually prove this with a bit of experimentation: A 1 meter x 1600 meter rectangle would have a perimeter of 3202 meters A 2 meter x 800 meter rectangle would have a perimeter of 1604 meters A 4 meter x 400 meter rectangle would have a perimeter of 808 meters .... Etc. A 40 meter x400 meter rectangle would have a perimeter of 160 meters With an area of 1600 square meters, the square would have dimensions of 40 meters x 40 meters --> meaning that the 'length' would be 40. Final Answer: GMAT assassins aren't born, they're made, Rich Hi EMPOWERgmatRichC I thin there is a small typo highlighted. It must be 40. Also, I have a question. Why did not you use the graph attached with the question? is something tricky or wrong? Thanks in advance Hi Mo2men, The graph is perfectly fine - and using the data within can get you to the correct answer without too much trouble. In my explanation, I opted to focus on the underlying math rule behind why this math 'works' - since while it is a relatively rare rule, you are more likely to see that rule than you are to see anything like this graph on Test Day. GMAT assassins aren't born, they're made, Rich _________________ 760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com # Rich Cohen Co-Founder & GMAT Assassin Special Offer: Save$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Re: Planning is in progress for a fenced, rectangular playground with an a &nbs [#permalink] 16 Nov 2018, 13:57
Display posts from previous: Sort by