Last visit was: 20 Nov 2025, 00:59 It is currently 20 Nov 2025, 00:59
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
User avatar
tejal777
Joined: 25 Oct 2008
Last visit: 09 Jan 2012
Posts: 360
Own Kudos:
6,913
 [1]
Given Kudos: 100
Location: Kolkata,India
Posts: 360
Kudos: 6,913
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
coelholds
Joined: 03 Jul 2009
Last visit: 09 Oct 2013
Posts: 81
Own Kudos:
Given Kudos: 13
Location: Brazil
Posts: 81
Kudos: 567
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Sunchaser20
Joined: 15 Apr 2008
Last visit: 28 Nov 2015
Posts: 28
Own Kudos:
Given Kudos: 8
Location: Moscow
Posts: 28
Kudos: 32
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
tejal777
Joined: 25 Oct 2008
Last visit: 09 Jan 2012
Posts: 360
Own Kudos:
Given Kudos: 100
Location: Kolkata,India
Posts: 360
Kudos: 6,913
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Guys this is a PR question and the answer is E..Please help
User avatar
sapphireka
Joined: 05 Jul 2009
Last visit: 01 Oct 2011
Posts: 132
Own Kudos:
Given Kudos: 19
Location: Australia
Concentration: General, Management & Org Behaviour
Schools:Chicago Booth class of 2012
WE 1: Consulting
WE 2: Small business/Start up
WE 3: Strategy - Large Corporate
Posts: 132
Kudos: 31
Kudos
Add Kudos
Bookmarks
Bookmark this Post
*bump*

This is incredibly hard. I'd love to see an explanation, I've tried everything...!
User avatar
mnpqxyzt
Joined: 03 Sep 2009
Last visit: 17 Oct 2009
Posts: 18
Own Kudos:
Given Kudos: 1
Posts: 18
Kudos: 34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
1) Insufficient
( f-1)/f = 1 - 1/f, hence
sum of C = f - (1 + 1/2 + 1/3 + ... + 1/f) = (f-1) + (1/2 + 1/3 + .... + 1/f)
g/(g+1) = 1- 1/(g+1), hence
sum of D = g - (1/2 + 1/3 + ... + 1/g+1)

So sum of C = sum of G if and only if f-1 = g

2)
median of C is 1/c or (1/c1 + 1/c2) /2
median of D is 1/d or (1/d1 + 1/d2) /2

We may have
1/c - 1/d = 3/43 or (1/c1 + 1/c2) /2 - ((1/d1 + 1/d2) /2) = 3/43 or
1/c - ((1/d1 + 1/d2) /2) = 3/43 or (1/c1 + 1/c2) /2 - 1/d = 3/43
we can not find c and d with only one equation like that
so insufficient


=>My answer is E

tejal777
ANYBODY?
avatar
gmate2010
Joined: 25 Aug 2009
Last visit: 26 Nov 2009
Posts: 96
Own Kudos:
Given Kudos: 12
Posts: 96
Kudos: 251
Kudos
Add Kudos
Bookmarks
Bookmark this Post
very tough question..

1.) This is insufficient,,we can prove by taking f = 3 ; g = 4 and f = 4 ; g = 3

2.) now, the condition arises;
Case1: f is odd, g is odd
Case2: f is even ,g is odd
Case3: f is odd , g is even
Case4: f is even, g is even

I tried to use al these cases, but did not get much luck, got stuck when either f or g is even

For Case1: i m getting, f -g = 46/43. (but we need f = g +1 for their sum to be equal)
=> their sum is not equal..
But, i am not sure, how to solve for other three cases..

PS:- I don't want to solve only one question on GDAY, so, i will pick either B or E in this case..and that will be a wild guess..
User avatar
GMAT TIGER
Joined: 29 Aug 2007
Last visit: 17 Aug 2011
Posts: 1,013
Own Kudos:
Given Kudos: 19
Posts: 1,013
Kudos: 1,783
Kudos
Add Kudos
Bookmarks
Bookmark this Post
tejal777
C is the finite sequence \(C_1\)=0,\(C_2\)=\(\frac{1}{2}\),\(C_3\)=\(\frac{2}{3}\)...determined by the equation \(C_f\)=\(\frac{f-1}{f}\)where f is a positive integer. D is a similiar finite sequence determined by the equation \(D_g\) = \(\frac{g}{g+1}\) where g is a positive integer, Is the sum of allthe values in C equal to the sum of all the values in D?

1.g \(\neq\)f
2.The difference between the median of C and the median of D is \(\frac{3}{43}\)


Phew this took a while to type!Anybody with a detailed explanation?

What is the source of the question? The question looks incorrrect to me because the difference (\(\frac{3}{43}\)) between the median of C and the median of D is not realistic.

Med C - Med D = 3/43

Since the denominator of the difference of the medians is a prime number (43), the denominators of the medians of both C and D are either 43 or its multiples.

Now we need to get 3/43. How do we get it?
Thats a tough calcalation. I did some excel calculation for the values of C and D. I could not get 3/43 from none of the median values for C and D.
Attachments

Median Diff.xls [186 KiB]
Downloaded 184 times

User avatar
mnpqxyzt
Joined: 03 Sep 2009
Last visit: 17 Oct 2009
Posts: 18
Own Kudos:
Given Kudos: 1
Posts: 18
Kudos: 34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
In my answer below, I just know that it's impossible to find medians of C and D, and even we have g != f (both statements), there's no difference because you can divide 3 cases f=g, f<g, f >g when you find C and D in 2).
In fact, with f=g+1 and the statement 2), I can prove that C and D don't exist

mnpqxyzt

2)
median of C is 1/c or (1/c1 + 1/c2) /2
median of D is 1/d or (1/d1 + 1/d2) /2

We may have
1/c - 1/d = 3/43 (1)
or (1/c1 + 1/c2) /2 - ((1/d1 + 1/d2) /2) = 3/43 (2)
or
1/c - ((1/d1 + 1/d2) /2) = 3/43 (3)
or (1/c1 + 1/c2) /2 - 1/d = 3/43 (4)
we can not find c and d with only one equation like that
so insufficient


=>My answer is E

tejal777
ANYBODY?
User avatar
maddy2u
Joined: 04 Dec 2009
Last visit: 19 Mar 2012
Posts: 60
Own Kudos:
Given Kudos: 11
Status:I am Midnight's Child !
GPA: 8.7
WE 1: Software Design and Development
Posts: 60
Kudos: 401
Kudos
Add Kudos
Bookmarks
Bookmark this Post
tejal777
C is the finite sequence \(C_1\)=0,\(C_2\)=\(\frac{1}{2}\),\(C_3\)=\(\frac{2}{3}\)...determined by the equation \(C_f\)=\(\frac{f-1}{f}\)where f is a positive integer.D is a similiar finite sequence determined by the equation \(D_g\) = \(\frac{g}{g+1}\) where g is a positive integer,Is the sum of allthe values in C equal to the sum of all the values in D?

1.g \(\neq\)f
2.The difference between the median of C and the median of D is \(\frac{3}{43}\)


Phew this took a while to type!Anybody with a detailed explanation?

I am not going into the logic of whether we can calculate the value of difference in median =\(\frac{3}{43}\) as it is not feasible to do in the GMAT exam. Let me tell the method that i followed here so that you can check with me back if it is not understandable.

IMO E because
From the stem, we can deduce the following

C: {\(0\) , \(\frac{1}{2}\) , \(\frac{2}{3}\), \(\frac{3}{4}\) ...... }
D { \(\frac{1}{2}\),\(\frac{2}{3}\), \(\frac{3}{4}\), \(\frac{4}{5}\) ... }

We can see that the sum of terms in C and D are the same iff g=f+1 ; For all other values it is different.
(1) f # g --> Not Sufficient
(2) Difference between median of C and D is 3/43 . This is nothing but the difference between (Median+1)th term and median th of C. Hence, we can calculate Median of C. Similarly, we can calculate median of D ( as median th term and (median-1) =3/43) . Knowing the median won't help us.

(1) +(2) => We still cannot find the value of Sum as it can be equal if g=f+1 and not equal for all other cases.

Thus answer should be E

P.S : i understand your difficulty in typing fractions . :lol:



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Data Sufficiency (DS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
Moderators:
Math Expert
105408 posts
GMAT Tutor
1924 posts