Last visit was: 21 Nov 2024, 21:13 It is currently 21 Nov 2024, 21:13
Decision Tracker
My Rewards
New comers' posts
New posts
Unanswered

Close

GRE Prep 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 GRE 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.

Go to My Error Log Learn more
Close

Request Expert Reply

Confirm Cancel
PREVIOUS TOPIC
NEXT TOPIC

c and d are positive

Tags :
Find Similar Topics  About  Add a Tag

Show Tags
Hide Tags

User avatar
D
Carcass
Verbal Expert
Joined: 18 Apr 2015
Posts: 30003
Own Kudos [?]: 36341 [7]
Given Kudos: 25927
Send PM
c and d are positive [#permalink] New post   25 Apr 2017, 02:58
1
Expert Reply
6
Bookmarks
00:00

Question Stats:

58% (01:00) correct 41% (01:09) wrong based on 391 sessions

Hide Show timer Statistics



c and d are positive

\(\frac{1}{c} = 1 + \frac{1}{d}\)

Quantity A
Quantity B
c
d


A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
ShowHide Answer
Official Answer
B
Most Helpful Community Reply
User avatar
P
GreenlightTestPrep
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 12196 [7]
Given Kudos: 136
Send PM

Top Member of the Month
c and d are positive [#permalink] New post   26 May 2017, 12:00
2
1
4
Bookmarks
Carcass wrote:


c and d are positive

\(\frac{1}{c} = 1 + \frac{1}{d}\)

Quantity A
Quantity B
c
d


A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.


Given: \(\frac{1}{c} = 1 + \frac{1}{d}\)

Multiply both sides of the equation by \(cd\) to get: \(d = cd + c\)

In Quantity B, replace \(d\) with \(cd + c\) to get:
Quantity A: \(c\)
Quantity B: \(cd + c\)

Subtract \(c\) from both sides of the equation to get:
Quantity A: \(0\)
Quantity B: \(cd\)

Since we're told \(c\) and \(d\) are both positive, we know that the product \(cd\) must be positive.

Answer: B

Cheers,
Brent
General Discussion
avatar
Fatemeh
Manager
Manager
Joined: 22 Feb 2018
Posts: 163
Own Kudos [?]: 214 [3]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   01 Apr 2018, 12:51
1
2
Bookmarks
Answer: B
1/c equals 1 + 1/d so 1/c is something bigger than 1/d,
1/c > 1/ d so d > c

EVEN for negative values this correlation is true.
avatar
novice07
Intern
Intern
Joined: 20 Mar 2018
Posts: 39
Own Kudos [?]: 127 [0]
Given Kudos: 0
GRE 1: Q163 V149

GRE 2: Q168 V162
GPA: 3.5
Send PM
Reviews Badge
Re: c and d are positive [#permalink] New post   04 Apr 2018, 07:46
2
Fraction 1/c is bigger than fraction 1/d as we have to add something to fraction 1/d to make it equal to fraction 1/c.

So, if 1/c > 1/d then c < d

Ans: B
avatar
Madhavi1990
Manager
Manager
Joined: 19 Mar 2018
Posts: 64
Own Kudos [?]: 37 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   16 Sep 2018, 23:10
Plug in +ve fraction values:

----0---1/4----1/4 +1
1/d 1/c

1/4 < 5/4 --< 1/d < 1/c
BUT
4> 4/5 ---> d> c
Qty B > Qty A
avatar
QuantumWonder
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   14 Dec 2018, 19:45
1
Carcass wrote:

This question is part of GREPrepClub - The Questions Vault Project



c and d are positive

\(\frac{1}{c} = 1 + \frac{1}{d}\)

Quantity A
Quantity B
c
d


A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.


There is an inherent contradiction in the given information, leading me to get the problem wrong. Let me explain.

Let's simplify the equation given. First we multiply everything by c and get

1 = c + c/d
Next we multiply by d
d = cd + c
d-cd = c
d(1-c) = c
d = c/(1-c)

If c is positive, then the 1-c in the denominator will be negative. Thus, d is negative. Thereby leading to a contradiction.
User avatar
P
GreenlightTestPrep
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 12196 [0]
Given Kudos: 136
Send PM

Top Member of the Month
Re: c and d are positive [#permalink] New post   15 Dec 2018, 06:42
2
QuantumWonder wrote:
Carcass wrote:


c and d are positive

\(\frac{1}{c} = 1 + \frac{1}{d}\)

Quantity A
Quantity B
c
d


A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.


There is an inherent contradiction in the given information, leading me to get the problem wrong. Let me explain.

Let's simplify the equation given. First we multiply everything by c and get

1 = c + c/d
Next we multiply by d
d = cd + c
d-cd = c
d(1-c) = c
d = c/(1-c)

If c is positive, then the 1-c in the denominator will be negative. Thus, d is negative. Thereby leading to a contradiction.


If c is positive, the denominator isn't necessarily negative.
For example, if c = 1/2, then d = 1

Cheers,
Brent
avatar
QuantumWonder
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   15 Dec 2018, 17:10
GreenlightTestPrep wrote:
QuantumWonder wrote:
Carcass wrote:


c and d are positive

\(\frac{1}{c} = 1 + \frac{1}{d}\)

Quantity A
Quantity B
c
d


A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.


There is an inherent contradiction in the given information, leading me to get the problem wrong. Let me explain.

Let's simplify the equation given. First we multiply everything by c and get

1 = c + c/d
Next we multiply by d
d = cd + c
d-cd = c
d(1-c) = c
d = c/(1-c)

If c is positive, then the 1-c in the denominator will be negative. Thus, d is negative. Thereby leading to a contradiction.


If c is positive, the denominator isn't necessarily negative.
For example, if c = 1/2, then d = 1

Cheers,
Brent


Thank you! That must have been from stress, can't believe I didn't see that. It's silly that it slipped me, double major in physics and mathematics and still have things like that slip me haha. GRE really challenges you to think very carefully, I like that aspect.
User avatar
HappyMathtutor
Manager
Manager
Joined: 01 Nov 2018
Posts: 87
Own Kudos [?]: 144 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   15 Dec 2018, 21:44
2
Expert Reply
Think of this

c and d are positive numbers

1/c > 1+1/d

this means that C is a positive fraction less than 1, since we can only get a number greater than 1 if 1 is divided by something smaller than 1.
if c is super small, like .01 then

100 > 1+1/d

d cant be less than or equal to .01.. if it is then

100 > 1+1/.01
becomes
100 > 1 + 100... which is not true so we know that if c is equal to .01, then d has to be greater than .01
thus, d is greater than c.

The answer is B
avatar
vigjna
Intern
Intern
Joined: 11 Oct 2018
Posts: 3
Own Kudos [?]: 2 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   17 Dec 2018, 03:39
1
given:1/c=1+1/d
solving equation gives d=cd+c
This implies D is Cd times greater than C
avatar
QuantumWonder
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   17 Dec 2018, 07:17
vigjna wrote:
given:1/c=1+1/d
solving equation gives d=cd+c
This implies D is Cd times greater than C


Nice fast solution mate.
avatar
Siddhaarth
Intern
Intern
Joined: 30 Aug 2020
Posts: 23
Own Kudos [?]: 23 [0]
Given Kudos: 0
GRE 1: Q165 V170
Send PM
Re: c and d are positive [#permalink] New post   19 Oct 2020, 17:55
1
Answer: b) B is greater
1/c = 1/d + 1

Multiply by cd on both sides of the equation

d = c + cd

Since c and d are both positive => cd > 0
This means that d > c
User avatar
bumpbot
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5030
Own Kudos [?]: 74 [0]
Given Kudos: 0
Send PM
Re: c and d are positive [#permalink] New post   30 Jan 2024, 13:26
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
gmatclubot
Re: c and d are positive [#permalink]
30 Jan 2024, 13:26
Moderators:
adewale223
GRE Instructor
84 posts
bronaugust
GRE Forum Moderator
37 posts
BrushMyQuant
Moderator
1111 posts
VibhuAnurag
GRE Instructor
234 posts

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

Main navigation

Partners

GRE Resources

www.ets.org/gre | About | Terms and Conditions and Privacy Policy | Prep Club for GRE Rules | Contact