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

 It is currently 23 Oct 2019, 19:00 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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  What is the difference between the areas of the squares ABCD and EFGC,

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

Hide Tags

GMATH Teacher P
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 935
What is the difference between the areas of the squares ABCD and EFGC,  [#permalink]

Show Tags

1
1 00:00

Difficulty:   35% (medium)

Question Stats: 71% (01:59) correct 29% (02:03) wrong based on 34 sessions

HideShow timer Statistics

GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order?

(1) The area of the shaded triangle CDE is 30.
(2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9.

_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
Senior Manager  G
Joined: 04 Aug 2010
Posts: 477
Schools: Dartmouth College
Re: What is the difference between the areas of the squares ABCD and EFGC,  [#permalink]

Show Tags

fskilnik wrote:
GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order?

(1) The area of the shaded triangle CDE is 30.
(2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9.

Statement 1:
Case 1: DC=10 and EC=6, with the result that CDE = (1/2)(10)(6) = 30
In this case, ABCD-EFGC = 10² - 6² = 100 - 36 = 64.

Case 2: DE=20 and EC=3, with the result that CDE = (1/2)(20)(3) = 30
In this case, ABCD-EFGC = 20² - 3² = 400 - 9 = 391.

Since ABCD-EFGC can be different values, INSUFFICIENT.

Statement 2:
Case 3: ABCD=25 and EFCG=9
In this case, ABCD-EFGC = 25 - 9 = 16.

Statement 2 implies the following:
DC²/EC² = 25/9
DC/EC = 5/3.
Case 1 satisfies the condition that DC/EC = 5/3.
In Case 1, ABCD-EFGC = 64.

Since ABCD-EFGC can be different values, INSUFFICIENT.

Statements combined:
Only Case 1 satisfies both statements.
In Case 1, ABCD-EFGC = 64.
SUFFICIENT.

.
_________________
GMAT and GRE Tutor
Over 1800 followers
GMATGuruNY@gmail.com
New York, NY
If you find one of my posts helpful, please take a moment to click on the "Kudos" icon.
Available for tutoring in NYC and long-distance.
GMATH Teacher P
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 935
What is the difference between the areas of the squares ABCD and EFGC,  [#permalink]

Show Tags

fskilnik wrote:
GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order?

(1) The area of the shaded triangle CDE is 30.
(2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9.

$$?\,\, = \,\,{S_{{\rm{ABCD}}}} - {S_{{\rm{EFGC}}}}$$

(Click on the image to have it "zoomed"!) $$\left. \matrix{ \left( {1 + 2} \right)\,\,\,\,? = \,{\left( {5k} \right)^2} - {\left( {3k} \right)^2} = 16{k^2} \hfill \cr 30 = {S_{\Delta {\rm{CDE}}}} = {{3k \cdot 5k} \over 2}\,\,\,\,\, \Rightarrow \,\,\,\,{k^2} = 4\,\,\, \hfill \cr} \right\}\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 16 \cdot 4\,\,\,\, \Rightarrow \,\,\,\,{\rm{SUFF}}.$$

The correct answer is (C).

We follow the notations and rationale taught in the GMATH method.

Regards,
Fabio.

POST-MORTEM: this problem is presented in our Quant Class 17 (not 15)... we thank our students for the correction!
_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
GMAT Club Legend  D
Joined: 18 Aug 2017
Posts: 5043
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: What is the difference between the areas of the squares ABCD and EFGC,  [#permalink]

Show Tags

#1
side of large square * side of small square = 60
side can be ( 30,2) , ( 20,3).. so on in sufficient

#2
ratio 25/9 or say side 5/3 in sufficient

from 1 & 2
base = 10 and side = 6 ;
ratio 5/3 area 25/9
IMO C

fskilnik wrote:
GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order?

(1) The area of the shaded triangle CDE is 30.
(2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9. Re: What is the difference between the areas of the squares ABCD and EFGC,   [#permalink] 27 Feb 2019, 04:44
Display posts from previous: Sort by

What is the difference between the areas of the squares ABCD and EFGC,

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne  