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

It is currently 22 Feb 2019, 16:46

Close

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
Your Progress

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.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
  • Free GMAT RC Webinar

     February 23, 2019

     February 23, 2019

     07:00 AM PST

     09:00 AM PST

    Learn reading strategies that can help even non-voracious reader to master GMAT RC. Saturday, February 23rd at 7 AM PT
  • FREE Quant Workshop by e-GMAT!

     February 24, 2019

     February 24, 2019

     07:00 AM PST

     09:00 AM PST

    Get personalized insights on how to achieve your Target Quant Score.

Triangle ABC has an area of 9. If AC is three times as long as CB, wha

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

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 53066
Triangle ABC has an area of 9. If AC is three times as long as CB, wha  [#permalink]

Show Tags

New post 09 Oct 2018, 00:57
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

92% (01:35) correct 8% (00:00) wrong based on 13 sessions

HideShow timer Statistics

Image
Triangle ABC has an area of 9. If AC is three times as long as CB, what is the length of AB?


(A) \(6\)

(B) \(3\sqrt{6}\)

(C) \(2\sqrt{15}\)

(D) \(4\sqrt{15}\)

(E) \(15\)


Attachment:
Capture (2).JPG
Capture (2).JPG [ 10.58 KiB | Viewed 377 times ]

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Manager
Manager
User avatar
S
Joined: 28 Aug 2018
Posts: 206
CAT Tests
Re: Triangle ABC has an area of 9. If AC is three times as long as CB, wha  [#permalink]

Show Tags

New post 09 Oct 2018, 01:05
Ans is option C 2√15

Bcz ac is 3x

Bc is x

Value of x comes to be √6

Therefore ab comes to be √60

Posted from my mobile device
_________________

"Press +1 KUDOS"

Be very critical of my Post
Ask as many questions of my post possible

VP
VP
User avatar
P
Joined: 31 Oct 2013
Posts: 1162
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
Re: Triangle ABC has an area of 9. If AC is three times as long as CB, wha  [#permalink]

Show Tags

New post 09 Oct 2018, 01:06
Bunuel wrote:
Image
Triangle ABC has an area of 9. If AC is three times as long as CB, what is the length of AB?


(A) \(6\)

(B) \(3\sqrt{6}\)

(C) \(2\sqrt{15}\)

(D) \(4\sqrt{15}\)

(E) \(15\)


Attachment:
Capture (2).JPG



AC =X

CB= 3x

Area = 1/2* x*3x


1/2 * x*3x = 9

x = \(\sqrt{6}\)


\(AB^2 =AC^2 +CB^2\)

AB^2 =\((\sqrt{6})^2 *(3\sqrt{6})^2\)

AB=\(\sqrt{60}\)
\(AB = 2\sqrt{15}\)


The best answer is C.
Senior PS Moderator
User avatar
V
Joined: 26 Feb 2016
Posts: 3343
Location: India
GPA: 3.12
Premium Member
Triangle ABC has an area of 9. If AC is three times as long as CB, wha  [#permalink]

Show Tags

New post 09 Oct 2018, 01:13
Image


In the triangle ABC, if the length of side CB is \(x\), the length of the side AC is \(3x\). (From the question stem)

Since this is a right-angled triangle, the length of AB(hypotenuse) is \(\sqrt{(3x)^2 + x^2} = \sqrt{10x^2}\)

We are told that the area of the triangle ABC is 9. Now, \(\frac{1}{2}*x*3x = 9\) -> \(3x^2 = 18\) -> \(x = \sqrt{6}\)

Therefore, the length of AB is \(\sqrt{10x^2}\) which is \(\sqrt{60}\) or \(2\sqrt{15}\)(Option C)

_________________

You've got what it takes, but it will take everything you've got

Intern
Intern
avatar
Joined: 03 Oct 2018
Posts: 4
Re: Triangle ABC has an area of 9. If AC is three times as long as CB, wha  [#permalink]

Show Tags

New post 09 Oct 2018, 01:14
Let bc = x, so ac=3x
We know that,
Area of traigle = 1/2*bc*ac
Or 9= x*3x/2
Or 9= 3x^2/2
Or 3x^2= 9
Or x^2= 3
So x= √3
So ac= 3√3
We know that,
Ab^2= ac^2+ bc^2
= (3√3)^2+ √3^2
= 9×3+3
=30
Ab=√30

Posted from my mobile device
Intern
Intern
avatar
Joined: 03 Oct 2018
Posts: 4
Re: Triangle ABC has an area of 9. If AC is three times as long as CB, wha  [#permalink]

Show Tags

New post 09 Oct 2018, 01:18
rumel1991 wrote:
Let bc = x, so ac=3x
We know that,
Area of traigle = 1/2*bc*ac
Or 9= x*3x/2
Or 9= 3x^2/2
Or 3x^2= 18
Or x^2= 6
So x= √6
So ac= 3√6
We know that,
Ab^2= ac^2+ bc^2
= (3√6)^2+ √6^2
= 9×6+6
=60
Ab=√60
=√4×15
2√15
Ans:2√15

Posted from my mobile device
GMAT Club Bot
Re: Triangle ABC has an area of 9. If AC is three times as long as CB, wha   [#permalink] 09 Oct 2018, 01:18
Display posts from previous: Sort by

Triangle ABC has an area of 9. If AC is three times as long as CB, wha

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.