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

It is currently 22 Oct 2019, 19:54

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

If a/b=2/3 which of the following is not true ?

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

Hide Tags

Find Similar Topics 
Board of Directors
User avatar
D
Joined: 01 Sep 2010
Posts: 3408
If a/b=2/3 which of the following is not true ?  [#permalink]

Show Tags

New post 25 May 2017, 12:56
2
Top Contributor
2
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

80% (01:07) correct 20% (01:18) wrong based on 223 sessions

HideShow timer Statistics

If \(\frac{a}{b}=\frac{2}{3}\) which of the following is not true ?

A) \(\frac{a+b}{b}=\frac{5}{3}\)

B) \(\frac{b}{b-a}=3\)

C) \(\frac{a-b}{b}=\frac{1}{3}\)

D) \(\frac{2a}{3b}=\frac{4}{9}\)

E) \(\frac{a+3b}{a}=\frac{11}{2}\)

_________________
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: If a/b=2/3 which of the following is not true ?  [#permalink]

Show Tags

New post 25 May 2017, 13:05
2
1
carcass wrote:
If \(\frac{a}{b}=\frac{2}{3}\) which of the following is not true ?

A) \(\frac{a+b}{b}=\frac{5}{3}\)

B) \(\frac{b}{b-a}=3\)

C) \(\frac{a-b}{b}=\frac{1}{3}\)

D) \(\frac{2a}{3b}=\frac{4}{9}\)

E) \(\frac{a+3b}{a}=\frac{11}{2}\)


One of the possible values of a and b is a = 2 and b = 3. In this case all options are true but C:

\((\frac{2-3}{3}=-\frac{1}{3})\neq \frac{1}{3}\).

Answer: C.

Similar question with several different approaches: https://gmatclub.com/forum/if-5x-4y-whi ... 34924.html
_________________
Board of Directors
User avatar
D
Joined: 01 Sep 2010
Posts: 3408
Re: If a/b=2/3 which of the following is not true ?  [#permalink]

Show Tags

New post 25 May 2017, 13:16
Top Contributor
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2815
Re: If a/b=2/3 which of the following is not true ?  [#permalink]

Show Tags

New post 31 May 2017, 19:15
carcass wrote:
If \(\frac{a}{b}=\frac{2}{3}\) which of the following is not true ?

A) \(\frac{a+b}{b}=\frac{5}{3}\)

B) \(\frac{b}{b-a}=3\)

C) \(\frac{a-b}{b}=\frac{1}{3}\)

D) \(\frac{2a}{3b}=\frac{4}{9}\)

E) \(\frac{a+3b}{a}=\frac{11}{2}\)


We are given that a/b = 2/3 or 3a = 2b.

Let’s simplify each answer choice to determine which one cannot be manipulated to yield 3a = 2b.

A) (a + b)/b = 5/3

3(a + b) = 5b

3a + 3b = 5b

3a = 2b

Since we have 3a = 2b, answer choice A is not correct.

B) b/(b - a) = 3

b = 3(b - a)

b = 3b - 3a

3a = 2b

Since we have 3a = 2b, answer choice B is not correct.

C) (a - b)/b = 1/3

3(a - b) = b

3a - 3b = b

3a = 4b

Since we have 3a = 4b, answer choice C is correct.

Alternative solution:

Let’s test each answer choice to determine which one is not true (keep in mind that a/b = 2/3).

A) (a + b)/b = 5/3

(a + b)/b = a/b + b/b = 2/3 + 1 = 5/3 → This is true.

B) b/(b - a) = 3

Notice that b/(b - a) = 3 means (b - a)/b = 1/3 when we reciprocate both sides of the equation.

(b - a)/b = b/b - a/b = 1 - 2/3 = ⅓ → This is true.

C) (a - b)/b = 1/3

(a - b)/b = a/b - b/b = 2/3 - 1 = -1/3 → So (a - b)/b = 1/3 is not true. This is the correct answer choice.

Answer: C
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Director
Director
avatar
G
Joined: 09 Mar 2018
Posts: 994
Location: India
Re: If a/b=2/3 which of the following is not true ?  [#permalink]

Show Tags

New post 06 Feb 2019, 23:17
carcass wrote:
If \(\frac{a}{b}=\frac{2}{3}\) which of the following is not true ?

A) \(\frac{a+b}{b}=\frac{5}{3}\)

B) \(\frac{b}{b-a}=3\)

C) \(\frac{a-b}{b}=\frac{1}{3}\)

D) \(\frac{2a}{3b}=\frac{4}{9}\)

E) \(\frac{a+3b}{a}=\frac{11}{2}\)


use values, a/b = 2/3

a = 2b / 3, a =2 b = 3

Only C doesn't satisfy when those values are used.
_________________
If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.
SVP
SVP
User avatar
P
Joined: 03 Jun 2019
Posts: 1746
Location: India
Premium Member Reviews Badge CAT Tests
If a/b=2/3 which of the following is not true ?  [#permalink]

Show Tags

New post 14 Sep 2019, 00:14
carcass wrote:
If \(\frac{a}{b}=\frac{2}{3}\) which of the following is not true ?

A) \(\frac{a+b}{b}=\frac{5}{3}\)

B) \(\frac{b}{b-a}=3\)

C) \(\frac{a-b}{b}=\frac{1}{3}\)

D) \(\frac{2a}{3b}=\frac{4}{9}\)

E) \(\frac{a+3b}{a}=\frac{11}{2}\)


Given: \(\frac{a}{b}=\frac{2}{3}\)

Asked: which of the following is not true ?

A) \(\frac{a+b}{b}=\frac{5}{3}\)
\(\frac{a+b}{b}= \frac{2+3}{3}= \frac{5}{3}\)
TRUE

B) \(\frac{b}{b-a}=3\)
\(\frac{b}{b-a}=3(3-2) = 3\)
TRUE

C) \(\frac{a-b}{b}=\frac{1}{3}\)
\(\frac{a-b}{b}=\frac{2-3}{3} = -\frac{1}{3} \neq \frac{1}{3}\)
NOT TRUE

D) \(\frac{2a}{3b}=\frac{4}{9}\)
\(\frac{2a}{3b}=\frac{2*2}{3*3}= \frac{4}{9}\)
TRUE

E) \(\frac{a+3b}{a}=\frac{11}{2}\)
\(\frac{a+3b}{a}= = \frac{2+3*3}{2} = \frac{11}{2}\)
TRUE

IMO C
_________________
"Success is not final; failure is not fatal: It is the courage to continue that counts."

Please provide kudos if you like my post. Kudos encourage active discussions.

My GMAT Resources: -

Efficient Learning
All you need to know about GMAT quant

Tele: +91-11-40396815
Mobile : +91-9910661622
E-mail : kinshook.chaturvedi@gmail.com
GMAT Club Bot
If a/b=2/3 which of the following is not true ?   [#permalink] 14 Sep 2019, 00:14
Display posts from previous: Sort by

If a/b=2/3 which of the following is not true ?

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





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