It is currently 20 Oct 2017, 15:22

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

The sum of all consecutive odd integers from −21 to 31, inclusive, is

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

Hide Tags

Verbal Forum Moderator
Verbal Forum Moderator
User avatar
Joined: 29 Apr 2015
Posts: 894

Kudos [?]: 1806 [0], given: 302

Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
GMAT ToolKit User Premium Member
The sum of all consecutive odd integers from −21 to 31, inclusive, is [#permalink]

Show Tags

New post 27 Jun 2015, 03:32
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

74% (01:26) correct 26% (01:30) wrong based on 122 sessions

HideShow timer Statistics

The sum of all consecutive odd integers from −21 to 31, inclusive, is

A. 130
B. 135
C. 150
D. 156
E. 235


[Reveal] Spoiler:
The sum of odd integers from -21 to 21 is zero because each negative value cancels out its positive counterpart. Based on this, add odd integers from 22 to 31 to get the sum of consecutive integers from -21 to 31.

23 + 25 + 27 + 29 + 31 = 135.
[Reveal] Spoiler: OA

_________________

Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.

Kudos [?]: 1806 [0], given: 302

Expert Post
3 KUDOS received
SVP
SVP
User avatar
G
Joined: 08 Jul 2010
Posts: 1835

Kudos [?]: 2279 [3], given: 51

Location: India
GMAT: INSIGHT
WE: Education (Education)
Reviews Badge
Re: The sum of all consecutive odd integers from −21 to 31, inclusive, is [#permalink]

Show Tags

New post 27 Jun 2015, 03:55
3
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
reto wrote:
The sum of all consecutive odd integers from −21 to 31, inclusive, is

A. 130
B. 135
C. 150
D. 156
E. 235




The sum of odd integers from -21 to 21 = - 21 - 19 - 17 ---------+17 + 19 + 21 + 23 + 25 + 27 + 29 + 31

The sum of odd integers from -21 to 21 = 0 + 5* 27 = 0 + 135 = 135

When the terms are separated by a constant amount then Mean = media = Average of first and last term

Sum of 23 + 25 + 27 + 29 + 31 = 27(mean) * 5(no. of terms) = 135


Answer: Option B
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Kudos [?]: 2279 [3], given: 51

Intern
Intern
avatar
Joined: 28 Dec 2015
Posts: 42

Kudos [?]: 3 [0], given: 62

Re: The sum of all consecutive odd integers from −21 to 31, inclusive, is [#permalink]

Show Tags

New post 30 Jun 2016, 22:06
-21 to +21=sum=0
Now add the rest of them
23+25+27+29+31=135

Kudos [?]: 3 [0], given: 62

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16636

Kudos [?]: 273 [0], given: 0

Premium Member
Re: The sum of all consecutive odd integers from −21 to 31, inclusive, is [#permalink]

Show Tags

New post 19 Aug 2017, 04:30
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 Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Kudos [?]: 273 [0], given: 0

Intern
Intern
avatar
B
Joined: 08 Jun 2015
Posts: 20

Kudos [?]: 2 [0], given: 36

Location: United States
Concentration: Finance, Economics
WE: Engineering (Other)
Re: The sum of all consecutive odd integers from −21 to 31, inclusive, is [#permalink]

Show Tags

New post 19 Aug 2017, 05:14
By using the formulas of AP Last term = First Term + (Number of terms - 1 ) X Difference, 31 = -21 + (n-1) X 2 ==> we get Number of terms = 27.
and by Sum of AP = n/2 X (First term + last term ), S = 27/2 X (-21+31) ==> we get Sum = 135.

Kudos [?]: 2 [0], given: 36

Intern
Intern
avatar
Joined: 12 May 2016
Posts: 4

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

Re: The sum of all consecutive odd integers from −21 to 31, inclusive, is [#permalink]

Show Tags

New post 19 Aug 2017, 06:18
The answer is B. From -21 to +21 is zero. Then, 23+25+27+29+31=135.

Sent from my General Mobile 4G Dual using GMAT Club Forum mobile app

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

Re: The sum of all consecutive odd integers from −21 to 31, inclusive, is   [#permalink] 19 Aug 2017, 06:18
Display posts from previous: Sort by

The sum of all consecutive odd integers from −21 to 31, inclusive, is

  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®.