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

It is currently 20 Aug 2018, 08:12

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

GMATPrep: Equal to n?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
avatar
Joined: 04 Dec 2008
Posts: 97
GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 01 Apr 2010, 20:21
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

50% (00:02) correct 50% (00:00) wrong based on 5 sessions

HideShow timer Statistics

If each term in the sum a1+a2............an is either 7 or 77 and the sum equals 350, which of the following could be equal to n?

A. 38
B. 39
C. 40
D. 41
E. 42

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2009
Posts: 275
Location: India
Concentration: General Management
Re: GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 01 Apr 2010, 22:51
joyseychow wrote:
If each term in the sum a1+a2............an is either 7 or 77 and the sum equals 350, which of the following could be equal to n?

A. 38
B. 39
C. 40
D. 41
E. 42


c.40

39*7 + 1*77 = 350. so n = 39 + 1 = 40
Senior Manager
Senior Manager
User avatar
Joined: 18 Jun 2009
Posts: 348
Location: San Francisco
Schools: Duke,Oxford,IMD,INSEAD
Re: GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 01 Apr 2010, 23:36
Approach the problem like this

first thing is we need a '0' in the units digits of the result ... so when you add a '3' to a '7' you get '0' in the units digit

The only number which provides a '3' in the units digit is that is 39*77 or 39*7 ... since the latter makes sense for a total of 350 we have

39*7 = 273 + 77 = 350
Manager
Manager
User avatar
Status: Completed GMAT on 22 Nov 2011
Joined: 08 Nov 2010
Posts: 132
Reviews Badge
Re: GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 16 May 2011, 22:22
Step 1:

If all the terms in the sum are 7, then we need 50 terms of 7. But in the solution there is no option of 50.

Step 2:

We have an option of substituting 77 in the terms of the equation.
So, if we have one 77 in the terms of the equation, then we have to have thirty nine terms of 7 i.e
39*7+77=350

We need 40 terms in the equation to equal 350. We have 40 as an option in the list of answers.
If we want to substitute two terms of 77, we need an option, which has less than 29 terms in the list of answers.

So, the obvious choice of answer is (C).
Current Student
avatar
Joined: 08 Jan 2009
Posts: 309
GMAT 1: 770 Q50 V46
Re: GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 17 May 2011, 05:24
(7x + 77y) = 350
7(x +11y) = 350
x + 11y = 50

Clearly if we let y = 1, then x = 39. Number of terms is 40. C.

Posted from my mobile device
Retired Moderator
avatar
B
Joined: 16 Nov 2010
Posts: 1458
Location: United States (IN)
Concentration: Strategy, Technology
Premium Member Reviews Badge
Re: GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 17 May 2011, 06:30
7-77-problem-solving-27636.html
_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

VP
VP
avatar
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1124
Re: GMATPrep: Equal to n?  [#permalink]

Show Tags

New post 17 May 2011, 08:24
39 1's and 40th element is 11.

40

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Re: GMATPrep: Equal to n? &nbs [#permalink] 17 May 2011, 08:24
Display posts from previous: Sort by

GMATPrep: Equal to n?

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

Events & Promotions

PREV
NEXT


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®.