GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 24 Feb 2020, 00:54 ### 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

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.  # If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?

Author Message
TAGS:

### Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 61407
If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  [#permalink]

### Show Tags 00:00

Difficulty:   35% (medium)

Question Stats: 73% (01:38) correct 27% (02:02) wrong based on 119 sessions

### HideShow timer Statistics

If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?

A. b/(1 - b)
B. (b - 1)/b
C. b/(b + 1)
D. (b + 1)/b
E. (1 - b)/b

_________________
Board of Directors D
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4841
Location: India
GPA: 3.5
Re: If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  [#permalink]

### Show Tags

1
1
Bunuel wrote:
If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?

A. b/(1 - b)
B. (b - 1)/b
C. b/(b + 1)
D. (b + 1)/b
E. (1 - b)/b

$$\frac{ab}{(a - b)}$$= 1

ab = a - b

Or, b = a - ab

or, b = a( 1 - b)

Or, $$\frac{b}{(1-b)}$$ = a

_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
EMPOWERgmat Instructor V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 16141
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  [#permalink]

### Show Tags

1
1
Hi All,

This question comes with a particular 'quirk' (one that you probably won't see on Test Day). The GMAT won't test you on the concept of undefined numbers (re: numbers divided by 0), so any time that this concept is a possibility, the question writers have to add a restriction that removes the option that a 0 could occur in the denominator.

Here, we're told that B CANNOT = 1, which is a bit strange because that restriction doesn't seem to impact the original equation much. In fact, it impacts JUST ONE of the answer choices - so you have to ask WHY that restriction is even there. It's actually because that one answer is the correct one.

GMAT assassins aren't born, they're made,
Rich
_________________
Target Test Prep Representative V
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 9461
Location: United States (CA)
Re: If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  [#permalink]

### Show Tags

Bunuel wrote:
If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?

A. b/(1 - b)
B. (b - 1)/b
C. b/(b + 1)
D. (b + 1)/b
E. (1 - b)/b

Simplifying, we have:

ab = a - b

b = a - ab

b = a(1 - b)

b/(1 - b) = a

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

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.

VP  D
Joined: 18 Dec 2017
Posts: 1121
Location: United States (KS)
GMAT 1: 600 Q46 V27 Re: If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  [#permalink]

### Show Tags

Well, I couldn't solve. So I thought to use options.

Option A : a=b/(1 - b)

If you solve you get the original equation back. Hence A is the right answer.

Also, the trick by Empower is neat.! (but as Rich said you probably won't see it on the test day)
_________________
The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long

Learn from the Legend himself: All GMAT Ninja LIVE YouTube videos by topic
You are missing on great learning if you don't know what this is: Project SC Butler
Target Test Prep Representative V
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 9461
Location: United States (CA)
Re: If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  [#permalink]

### Show Tags

Bunuel wrote:
If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?

A. b/(1 - b)
B. (b - 1)/b
C. b/(b + 1)
D. (b + 1)/b
E. (1 - b)/b

Simplifying, we have:

ab = a - b

ab - a = -b

a(b - 1) = -b

a = -b / (b - 1)

a = b / (1 - b)

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

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. Re: If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?   [#permalink] 18 Jan 2020, 04:08
Display posts from previous: Sort by

# If b ≠ 1 and if ab/(a - b) = 1, what is the value of a in terms of b?  