|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
25 Feb 2019, 14:49
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
66% (02:10) correct
34%
(01:51)
wrong
based on 86
sessions
History
Date
Time
Result
Not Attempted Yet
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.
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.
25 Feb 2019, 15:23
Kudos
Bookmarks
fskilnik
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.
.
25 Feb 2019, 18:42
Kudos
Bookmarks
fskilnik
\(?\,\, = \,\,{S_{{\rm{ABCD}}}} - {S_{{\rm{EFGC}}}}\)
(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!
