It is currently 19 Nov 2017, 03:08

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If S is the sum of reciprocals of a list of consecutive

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Manager
Manager
avatar
Joined: 04 Mar 2012
Posts: 50

Kudos [?]: 298 [0], given: 10

If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 16 May 2012, 09:35
10
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

66% (00:54) correct 34% (00:58) wrong based on 501 sessions

HideShow timer Statistics

If S is the sum of reciprocals of a list of consecutive integers from 45 to 54, inclusive, S is approximately equal to

A. 0.1
B. 0.2
C. 0.3
D. 0.4
E. 0.5
[Reveal] Spoiler: OA

Last edited by Bunuel on 13 Aug 2014, 03:12, edited 1 time in total.
Added the OA.

Kudos [?]: 298 [0], given: 10

Expert Post
2 KUDOS received
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42249

Kudos [?]: 132649 [2], given: 12329

Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 16 May 2012, 09:42
2
This post received
KUDOS
Expert's post
10
This post was
BOOKMARKED
gmihir wrote:
If S is the sum of reciprocals of a list of consecutive integers from 45 to 54, inclusive, S is approximately equal to

A. 0.1
B. 0.2
C. 0.3
D. 0.4
E. 0.5

Sorry, don't have an official answer.


We need to find the approximate value of 1/45+1/46+1/47+1/48+1/49+1/50+1/51+1/52+1/53+1/54. Now, the sum of these 10 terms will be very close to 10 times 1/50, which is 0.02*10=0.2.

Answer: B.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 132649 [2], given: 12329

Intern
Intern
avatar
Joined: 11 Jul 2012
Posts: 42

Kudos [?]: 7 [0], given: 0

Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 05 Nov 2012, 15:18
I got 0.2 too (B). Please help. Here is my approach
(1/45) + (1/46) + .....+(1/54) = (45-44)/45 +(46-45)/46 +.....+(54-53)/54
= 10 -(44/45 + 45/46 + ...53/54). Each term in the bracket is > 0.977, and there are ten of them. Then their sum is roughly 9.8
10-9.8 = 0.2. But is this doable in 2 mn under stress and heat?
Brother Karamazov



Brother Karamazov

Kudos [?]: 7 [0], given: 0

Intern
Intern
avatar
Status: wants to beat the gmat
Joined: 18 Jul 2012
Posts: 20

Kudos [?]: 9 [0], given: 1

Location: United States
Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 06 Nov 2012, 13:47
my method was 1/45 + 1/46 + ... => 10/45 ~ 2/9 ~ .2

Kudos [?]: 9 [0], given: 1

7 KUDOS received
Senior Manager
Senior Manager
User avatar
Joined: 13 Aug 2012
Posts: 458

Kudos [?]: 557 [7], given: 11

Concentration: Marketing, Finance
GPA: 3.23
GMAT ToolKit User
Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 19 Dec 2012, 03:59
7
This post received
KUDOS
5
This post was
BOOKMARKED
gmihir wrote:
If S is the sum of reciprocals of a list of consecutive integers from 45 to 54, inclusive, S is approximately equal to

A. 0.1
B. 0.2
C. 0.3
D. 0.4
E. 0.5

Sorry, don't have an official answer.


Solved this using Bunuel's technique that I saw on another similar problem.

S = \(\frac{1}{45}+\frac{1}{46}+...+\frac{1}{54}\)

Get number of terms: \(54 - 45 + 1 = 10\)

Get lower limit: \(10*\frac{1}{54}=\frac{5}{27}=0.18\)
Get upper limit: \(10*\frac{1}{45}=\frac{2}{9}=0.22\)

\(0.18<S<0.22\)

Answer: B
_________________

Impossible is nothing to God.

Kudos [?]: 557 [7], given: 11

Expert Post
Senior Manager
Senior Manager
User avatar
Joined: 20 Aug 2015
Posts: 396

Kudos [?]: 349 [0], given: 10

Location: India
GMAT 1: 760 Q50 V44
Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 09 Nov 2015, 03:15
gmihir wrote:
If S is the sum of reciprocals of a list of consecutive integers from 45 to 54, inclusive, S is approximately equal to

A. 0.1
B. 0.2
C. 0.3
D. 0.4
E. 0.5


Such questions do not test your calculations. (In fact most of GMAT questions) They test your logic and how easily can you simplify a problem.
That is why an approximate result is asked and not the absolute value.


Out of the given numbers, from 45 to 54, carrying out calculations with 50 would be easiest.

Hene instead of 1/45 + 1/46 + ... 1/50 + ... + 1/54,
We can increase some terms and decrease some terms by changing the numbers with 50

Hence we have a sequence = 1/50 + 1/50 + ... + 1/50 (Total 20 terms)
= 10/50 = 1/5 = 0.2 approximately
Option B
_________________

Reach out to us at bondwithus@gmatify.com

Image

Kudos [?]: 349 [0], given: 10

Intern
Intern
avatar
B
Joined: 26 Dec 2016
Posts: 20

Kudos [?]: 3 [0], given: 13

Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 13 Feb 2017, 05:20
TeamGMATIFY wrote:
gmihir wrote:
If S is the sum of reciprocals of a list of consecutive integers from 45 to 54, inclusive, S is approximately equal to

A. 0.1
B. 0.2
C. 0.3
D. 0.4
E. 0.5


Such questions do not test your calculations. (In fact most of GMAT questions) They test your logic and how easily can you simplify a problem.
That is why an approximate result is asked and not the absolute value.


Out of the given numbers, from 45 to 54, carrying out calculations with 50 would be easiest.

Hene instead of 1/45 + 1/46 + ... 1/50 + ... + 1/54,
We can increase some terms and decrease some terms by changing the numbers with 50

Hence we have a sequence = 1/50 + 1/50 + ... + 1/50 (Total 20 terms)
= 10/50 = 1/5 = 0.2 approximately
Option B


Hi,

aren't there 10 terms and not 20 ?

regards

Kudos [?]: 3 [0], given: 13

Expert Post
1 KUDOS received
Target Test Prep Representative
User avatar
S
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1684

Kudos [?]: 902 [1], given: 5

Re: If S is the sum of reciprocals of a list of consecutive [#permalink]

Show Tags

New post 14 Feb 2017, 16:55
1
This post received
KUDOS
Expert's post
gmihir wrote:
If S is the sum of reciprocals of a list of consecutive integers from 45 to 54, inclusive, S is approximately equal to

A. 0.1
B. 0.2
C. 0.3
D. 0.4
E. 0.5


We need to determine the approximate value of the sum of the reciprocals from 45 to 54 inclusive; thus, we need the approximate value of the following:

1/45 + 1/46 + 1/47 + 1/48 + 1/49 + 1/50 + 1/51 + 1/52 + 1/53 + 1/54

Rather than adding each of these numbers (which would be incredibly time-consuming), let’s strategically select one of the fractions in our list and add it to itself 10 times. That sum will give us an approximate value for S.

Scanning the list, we see the best number to add to itself 10 times is 1/50. However, instead of actually adding 1/50 ten times, we will simply multiply it by 10:

1/50 x 10 = 10/50 = 1/5 = 0.2

Thus, we see that S is approximately 0.2.

Answer: B
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 902 [1], given: 5

Re: If S is the sum of reciprocals of a list of consecutive   [#permalink] 14 Feb 2017, 16:55
Display posts from previous: Sort by

If S is the sum of reciprocals of a list of consecutive

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.