Last visit was: 14 Jul 2024, 23:16 It is currently 14 Jul 2024, 23:16
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
SORT BY:
Date
Tags:
Show Tags
Hide Tags
Alum
Joined: 12 Aug 2015
Posts: 2271
Own Kudos [?]: 3195 [30]
Given Kudos: 893
GRE 1: Q169 V154
Send PM
Most Helpful Reply
GMAT Club Legend
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 6805
Own Kudos [?]: 30800 [11]
Given Kudos: 799
Location: Canada
Send PM
General Discussion
Manager
Manager
Joined: 28 Jun 2016
Posts: 153
Own Kudos [?]: 192 [1]
Given Kudos: 99
Location: Canada
Concentration: Operations, Entrepreneurship
Send PM
Manager
Manager
Joined: 24 Jul 2016
Posts: 67
Own Kudos [?]: 14 [0]
Given Kudos: 5
Location: United States (MI)
GMAT 1: 730 Q51 V40
GPA: 3.6
Send PM
Re: Which of the following fractions can be written as the difference of r [#permalink]
stonecold wrote:
Which of the following fractions can be written as the difference of reciprocals of two consecutive integers?

A. 1/100
B. 1/121
C. 1/45
D. 1/56
E. 3/72
Must be D. 1/56 since 56=7x8. The difference will be of the form 1/a X (a+1)


Sent from my iPhone using GMAT Club Forum mobile app
Manager
Manager
Joined: 03 Aug 2017
Posts: 76
Own Kudos [?]: 25 [0]
Given Kudos: 85
Send PM
Re: Which of the following fractions can be written as the difference of r [#permalink]
stonecold wrote:
Which of the following fractions can be written as the difference of reciprocals of two consecutive integers?

A. 1/100
B. 1/121
C. 1/45
D. 1/56
E. 3/72



This is how I solved

let The no be x and x+1 .
Which means the reciprocals = 1/x + 1/( X+1) which also means 2 consecutive integer should add upto the no.

Check ans choice and see which no is the multiplication of two consecutive nos
eg : a) 100 = 10 * 10 so rule out
c) 45 = 7*6 = 42+3 so rule out
d) 56 = 7*8 = 56 keep
e) 72 = 9*8 = keep

We're left with D and E.
Since E is not in the correct format (with 1 in the numerator), we can ELIMINATE E
Senior Manager
Senior Manager
Joined: 15 Feb 2018
Posts: 424
Own Kudos [?]: 385 [0]
Given Kudos: 2380
Send PM
Which of the following fractions can be written as the difference of r [#permalink]
Similar question to: https://gmatclub.com/forum/which-of-the ... 72318.html

I feel it is wrong to eliminate E based on having 3 in the numerator. Simplify the fraction and see that it is 1/24, now it can't.

Very similar to terminating decimal questions where it has 3/30 and the numerator and denominator need to be simplified to see that only 2s and 5s are in the denominator
GMAT Club Legend
GMAT Club Legend
Joined: 03 Jun 2019
Posts: 5275
Own Kudos [?]: 4182 [1]
Given Kudos: 160
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Send PM
Re: Which of the following fractions can be written as the difference of r [#permalink]
1
Bookmarks
stonecold wrote:
Which of the following fractions can be written as the difference of reciprocals of two consecutive integers?

A. 1/100
B. 1/121
C. 1/45
D. 1/56
E. 3/72


1/56 = 1/7-1/8

IMO D

Posted from my mobile device
Manager
Manager
Joined: 11 Jul 2018
Posts: 69
Own Kudos [?]: 32 [1]
Given Kudos: 267
Location: India
GMAT 1: 640 Q48 V30
GMAT 2: 710 Q49 V38
Send PM
Re: Which of the following fractions can be written as the difference of r [#permalink]
1
Kudos
stonecold wrote:
Which of the following fractions can be written as the difference of reciprocals of two consecutive integers?

A. 1/100
B. 1/121
C. 1/45
D. 1/56
E. 3/72



\(\frac{1}{x}-\frac{1}{(x+1)}=\frac{1}{x*(x+1)}\)

note that the consecutive integers x and x+1 product will always be even. So straight away eliminate B and C. Now look for other options. E reduce to the simplest form. Now you can see that the only D satisfies the condition, a product of 7 and 8
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 33970
Own Kudos [?]: 851 [0]
Given Kudos: 0
Send PM
Re: Which of the following fractions can be written as the difference of r [#permalink]
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.
GMAT Club Bot
Re: Which of the following fractions can be written as the difference of r [#permalink]
Moderator:
Math Expert
94342 posts