It is currently 23 Nov 2017, 04:48

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

Events & Promotions in June
Open Detailed Calendar

If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) =

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42323

Kudos [?]: 133100 [0], given: 12408

If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) = [#permalink]

Show Tags

New post 05 Nov 2017, 09:40
Expert's post
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

87% (01:15) correct 13% (01:41) wrong based on 53 sessions

HideShow timer Statistics

Kudos [?]: 133100 [0], given: 12408

Director
Director
avatar
P
Joined: 22 May 2016
Posts: 999

Kudos [?]: 347 [0], given: 594

If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) = [#permalink]

Show Tags

New post 05 Nov 2017, 10:29
Bunuel wrote:
If \(\frac{c-a}{c-b} = 2\), then \(\frac{5b-5a}{c-a} =\)

A. 0.5
B. 1
C. 1.5
D. 2
E. 2.5

Choose values that make the equation true. Use values to solve. I used two sets. The algebra here looks time-consuming. Choosing values was quick.

\(\frac{c-a}{c-b} = 2\)

\(c = 8\)
\(a = 4\)
\(b = 6\)

Chosen values satisfy the equation:
\(\frac{8-4}{8-6}=\frac{4}{2} = 2\)

\(\frac{5b-5a}{c-a} =?\)

\(\frac{5(6)-5(4)}{8-4}=\frac{(30-20)}{4}=\frac{10}{4}= 2.5\)

Check:

\(\frac{c-a}{c-b} = 2\)

\(c = 10\)
\(a = 4\)
\(b = 7\)

\(\frac{10-4}{10-7}=\frac{6}{3} = 2\)

\(\frac{5b-5a}{c-a} =?\)

\(\frac{5(7)-5(4)}{10-4}=\frac{(35-20)}{6}=\frac{15}{6}= 2.5\)

Answer E

Last edited by genxer123 on 05 Nov 2017, 10:34, edited 1 time in total.

Kudos [?]: 347 [0], given: 594

1 KUDOS received
Moderator
avatar
D
Joined: 22 Jun 2014
Posts: 943

Kudos [?]: 466 [1], given: 113

Location: India
Concentration: General Management, Technology
GMAT 1: 540 Q45 V20
GPA: 2.49
WE: Information Technology (Computer Software)
Premium Member CAT Tests
Re: If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) = [#permalink]

Show Tags

New post 05 Nov 2017, 10:32
1
This post received
KUDOS
Bunuel wrote:
If \(\frac{c-a}{c-b} = 2\), then \(\frac{5b-5a}{c-a} =\)

A. 0.5
B. 1
C. 1.5
D. 2
E. 2.5


\(\frac{c-a}{c-b} = 2\)

\(c-a = 2 * c-b\)

\(c-a = 2c - 2b\)

\(2b-a = c\)

\(b + b - a = c\)

\(b-a = c-b\)

\(5 * \frac{b-a}{c-a}\)

\(5 * \frac{c-b}{c-a}\)

\(5 * \frac{1}{2}\)

\(2.5\)
_________________

---------------------------------------------------------------
Target - 720-740
http://gmatclub.com/forum/information-on-new-gmat-esr-report-beta-221111.html
http://gmatclub.com/forum/list-of-one-year-full-time-mba-programs-222103.html

Kudos [?]: 466 [1], given: 113

1 KUDOS received
BSchool Forum Moderator
User avatar
D
Joined: 26 Feb 2016
Posts: 1624

Kudos [?]: 696 [1], given: 17

Location: India
Concentration: General Management, Leadership
WE: Sales (Retail)
Premium Member CAT Tests
If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) = [#permalink]

Show Tags

New post 05 Nov 2017, 11:08
1
This post received
KUDOS
We have been given that \(\frac{c-a}{c-b} = 2\)

Cross multiplying we get c-a = 2c-2b. Therefore c = 2b-a

Now, we need to find the value of \(\frac{5b-5a}{c-a}\)

This can be further simplified as \(\frac{5(b-a)}{c-a} = \frac{5(b-a)}{2b-2a} = \frac{5(b-a)}{2(b-a)} = 2.5\)(Option E)
_________________

Stay hungry, Stay foolish

2017-2018 MBA Deadlines

Class of 2020: Rotman Thread | Schulich Thread
Class of 2019: Sauder Thread

Kudos [?]: 696 [1], given: 17

Expert Post
Target Test Prep Representative
User avatar
S
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1713

Kudos [?]: 914 [0], given: 5

Re: If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) = [#permalink]

Show Tags

New post 08 Nov 2017, 17:38
Bunuel wrote:
If \(\frac{c-a}{c-b} = 2\), then \(\frac{5b-5a}{c-a} =\)

A. 0.5
B. 1
C. 1.5
D. 2
E. 2.5


Let’s multiply both sides of the given equation by c - b:

c - a = 2c - 2b

2b - a = c

Let’s rewrite the given expression as follows:

(5b - 5a)/(c - a) = (5/2)[(2b - 2a)/(c - a)]

Note that (2b - 2a)/(c - a) = (2b - a - a)/(c - a).

Substituting c for 2b - a in the numerator, we obtain (c - a)/(c - a) = 1.

Thus, (5b - 5a)/(c - a) = (5/2)[(2b - 2a)/(c - a)] = (5/2)(1) = 2.5.

Answer: E
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 914 [0], given: 5

Re: If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) =   [#permalink] 08 Nov 2017, 17:38
Display posts from previous: Sort by

If (c-a)/(c-b) = 2, then (5b-5a)/(c-a) =

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


GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.