Find all School-related info fast with the new School-Specific MBA Forum

It is currently 27 Aug 2014, 19:13

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Number systems

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 10 Jan 2010
Posts: 117
GPA: 4
WE: Programming (Computer Software)
Followers: 0

Kudos [?]: 42 [0], given: 33

GMAT Tests User
Number systems [#permalink] New post 04 Jan 2012, 16:58
1/100 + 1/101 + 1/102 + ..... 1/110?.

Can somebody let me know, how to solve these kind of problems?.
_________________

-If you like my post, consider giving KUDOS

Intern
Intern
avatar
Joined: 01 Jan 2012
Posts: 10
Followers: 0

Kudos [?]: 2 [0], given: 0

Re: Number systems [#permalink] New post 04 Jan 2012, 18:08
There is really no quick and dirty way to do this that I know of. You can get a close approximation by taking the average value of the first and last terms and multiplying by the number of terms (in this case 11*1/105). If you need to be exact this can be done by adding all permutations of the denominators in the numerator and the new denominator will be the product of all the old denominators. Perhaps if you posted a few answer choices more specific help could be given.
Expert Post
Manhattan GMAT Instructor
User avatar
Joined: 22 Mar 2011
Posts: 354
Followers: 124

Kudos [?]: 217 [0], given: 10

Re: Number systems [#permalink] New post 07 Jan 2012, 12:15
Expert's post
Yeah, this would be kind of a disaster to solve precisely, so you're not likely to see it on the GMAT. However, you might see something where each of the terms had a common factor that you could pull out, or something like that. Did you have a particular problem in mind?
_________________


Dmitry Farber | Manhattan GMAT Instructor | New York


Manhattan GMAT Discount | Manhattan GMAT Course Reviews | View Instructor Profile |
Manhattan GMAT Reviews

Senior Manager
Senior Manager
avatar
Status: D-Day is on February 10th. and I am not stressed
Affiliations: American Management association, American Association of financial accountants
Joined: 12 Apr 2011
Posts: 275
Location: Kuwait
Schools: Columbia university
Followers: 4

Kudos [?]: 37 [0], given: 52

GMAT Tests User
Re: Number systems [#permalink] New post 07 Jan 2012, 13:04
you can get the sum by multiplying the average of numbers by the number of elements

sum=average of numbers * number of elements

we have 11 elements 100 to 110===> (110-100+1=11)
if we have a consecutive odd number of elements then the average is the middle number which 105

so sum is the product of 1/105 time 11
so, 11/105
_________________

Sky is the limit

Expert Post
Manhattan GMAT Instructor
User avatar
Joined: 22 Mar 2011
Posts: 354
Followers: 124

Kudos [?]: 217 [0], given: 10

Re: Number systems [#permalink] New post 07 Jan 2012, 13:15
Expert's post
manalq8, that approach only works for consecutive integers, because they are evenly spaced. Since the consecutive integers are in the denominator here, the terms are not evenly spaced (i.e. the difference between 1/100 and 1/101 is not the same as the difference between 1/101 and 1/102). As joeshmo pointed out, the averaging approach would not get us a precise answer for this problem.

To illustrate, let's look at a simpler set of fractions:

1/1 + 1/2 + 1/3 =

If we multiply the median by the number of terms, we'd say the total is 3/2. However, the actual total is 11/6, which is about 22% greater than the projected answer. Also, notice that in this case, the average of the first and last terms does not equal the median. (1/1 + 1/3)/2 = (4/3)/2=4/6 = 2/3 If we average all 3 terms, we get yet another result (11/18). You can try this with any set of fractions and you'll get similar results. The consecutive numebr tricks are great, but they only work if the actual terms in question are evenly spaced!
_________________


Dmitry Farber | Manhattan GMAT Instructor | New York


Manhattan GMAT Discount | Manhattan GMAT Course Reviews | View Instructor Profile |
Manhattan GMAT Reviews

Intern
Intern
avatar
Joined: 06 Jan 2012
Posts: 32
Location: United States
GMAT 1: Q48 V30
Followers: 0

Kudos [?]: 8 [0], given: 5

Re: Number systems [#permalink] New post 13 Jan 2012, 15:38
How would you actually solve this problem?
Manually add the numbers
_________________

-If you like my post, consider giving KUDOS

Re: Number systems   [#permalink] 13 Jan 2012, 15:38
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic Number systems maheshsrini 5 04 Jan 2012, 16:58
1 Number System!! DeeptiM 5 26 Aug 2011, 10:50
Number System!! DeeptiM 3 18 Aug 2011, 10:47
number system einstein10 3 18 Apr 2010, 23:42
Number system KocharRohit 1 06 Nov 2009, 00:31
Display posts from previous: Sort by

Number systems

  Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group and phpBB SEO

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®.