GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 18 Oct 2018, 22:26

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

The sum of n consecutive positive integers is 45. What is the value of

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50000
The sum of n consecutive positive integers is 45. What is the value of  [#permalink]

Show Tags

New post 11 Apr 2018, 09:21
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

46% (01:38) correct 54% (01:48) wrong based on 58 sessions

HideShow timer Statistics

Manager
Manager
User avatar
S
Joined: 17 Jan 2017
Posts: 61
Premium Member
The sum of n consecutive positive integers is 45. What is the value of  [#permalink]

Show Tags

New post 11 Apr 2018, 10:01
2
Bunuel wrote:
The sum of n consecutive positive integers is 45. What is the value of n?

(1) n is odd
(2) n >= 9


Five ways to get 45 out of consecutive integers.
n=2: 22+23
n=3: 14+15+16
n=5: 7+8+9+10+11
n=6: 5+6+7+8+9+10
n=9: 1+2+3+4+5+6+7+8+9

(1) n=3, n=5, n=9
INSUFFICIENT

(2) n=9 remains
SUFFICIENT

Ans. (B)
Intern
Intern
avatar
B
Joined: 28 Apr 2014
Posts: 49
GMAT 1: 640 Q50 V25
GMAT ToolKit User CAT Tests
Re: The sum of n consecutive positive integers is 45. What is the value of  [#permalink]

Show Tags

New post 11 Apr 2018, 10:31
St1 gives lot of options
St2: unique set of 1 to 9
IMO B
Senior Manager
Senior Manager
User avatar
G
Joined: 29 Dec 2017
Posts: 389
Location: United States
Concentration: Marketing, Technology
GMAT 1: 630 Q44 V33
GMAT 2: 690 Q47 V37
GMAT 3: 710 Q50 V37
GPA: 3.25
WE: Marketing (Telecommunications)
The sum of n consecutive positive integers is 45. What is the value of  [#permalink]

Show Tags

New post 11 Apr 2018, 11:39
1
Bunuel wrote:
The sum of n consecutive positive integers is 45. What is the value of n?

(1) n is odd
(2) n >= 9


S = ( a(1)+a(n) )*n / 2 ==> 2a(1) + n - 1 = 90/n ==> a(1)= (90/n-n+1)/2


1)n is odd.

If n=5, then a(1)= (90/5-5+1)/2 = 7, check 7+8+9+10+11 = 45

If n=9, then a(1)= (90/9-9+1)/2 = 1, check 1+2+3+4+5+6+7+8+9 = 45 (NOT SUFF)

2)n >= 9

If n=9, then a(1)= (90/9-9+1)/2 = 1, check 1+2+3+4+5+6+7+8+9 = 45

If n=10, then a(1)= (90/10-10+1)/2 = 0, but a(1)>0 (SUFF)
For other n>9 a(1) will be <0, which contradicts our condition a(1)>0

Answer (B)
GMAT Club Bot
The sum of n consecutive positive integers is 45. What is the value of &nbs [#permalink] 11 Apr 2018, 11:39
Display posts from previous: Sort by

The sum of n consecutive positive integers is 45. What is the value of

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.