Last visit was: 19 Jul 2025, 20:47 It is currently 19 Jul 2025, 20:47
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
Sub 505 Level|   Algebra|   Fractions and Ratios|               
User avatar
carcass
User avatar
Board of Directors
Joined: 01 Sep 2010
Last visit: 19 Jul 2025
Posts: 4,730
Own Kudos:
36,205
 [22]
Given Kudos: 4,813
Posts: 4,730
Kudos: 36,205
 [22]
4
Kudos
Add Kudos
18
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Jul 2025
Posts: 102,627
Own Kudos:
742,809
 [8]
Given Kudos: 98,235
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,627
Kudos: 742,809
 [8]
5
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
General Discussion
User avatar
carcass
User avatar
Board of Directors
Joined: 01 Sep 2010
Last visit: 19 Jul 2025
Posts: 4,730
Own Kudos:
36,205
 [1]
Given Kudos: 4,813
Posts: 4,730
Kudos: 36,205
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,996
Own Kudos:
7,952
 [1]
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,996
Kudos: 7,952
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
carcass
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
User avatar
KanishkM
Joined: 09 Mar 2018
Last visit: 18 Dec 2021
Posts: 765
Own Kudos:
Given Kudos: 123
Location: India
Posts: 765
Kudos: 493
Kudos
Add Kudos
Bookmarks
Bookmark this Post
carcass
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.
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 19 Jul 2025
Posts: 5,703
Own Kudos:
Given Kudos: 161
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
GMAT 1: 690 Q50 V34
Posts: 5,703
Kudos: 5,238
Kudos
Add Kudos
Bookmarks
Bookmark this Post
carcass
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
User avatar
Abhishek009
User avatar
Board of Directors
Joined: 11 Jun 2011
Last visit: 18 Jul 2025
Posts: 5,965
Own Kudos:
Given Kudos: 463
Status:QA & VA Forum Moderator
Location: India
GPA: 3.5
WE:Business Development (Commercial Banking)
Posts: 5,965
Kudos: 5,162
Kudos
Add Kudos
Bookmarks
Bookmark this Post
carcass
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) \(\frac{a+3b}{a}=\frac{11}{2}\)
Clearly (C)

\(\frac{2-3}{3}=\frac{-1}{3}\)
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,453
Own Kudos:
Posts: 37,453
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102627 posts
PS Forum Moderator
698 posts