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

 It is currently 20 Jun 2018, 10:06

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# DS: t divided by 7

Author Message
Manager
Joined: 14 Jun 2007
Posts: 158
Location: Vienna, Austria
Re: DS: t divided by 7 [#permalink]

### Show Tags

08 Sep 2008, 01:47
friends, whats the OA ??
Current Student
Joined: 04 Jan 2005
Posts: 282
Location: Milan
Schools: Wharton, LBS, UChicago, Kellogg MMM (Donald Jacobs Scholarship), Stanford, HBS
Re: DS: t divided by 7 [#permalink]

### Show Tags

08 Sep 2008, 05:18
judokan,

as per the second question, I tried picking numbers:

65 (sum of digits 11), remainder 2
92 (sum of digits 11), remainder 2
499 (sum of digits 22), remainder 4
6999 (sum of digits 33), remainder 6

how could it be A? Or do I miss something in the question?
Senior Manager
Joined: 19 Mar 2008
Posts: 345
Re: DS: t divided by 7 [#permalink]

### Show Tags

08 Sep 2008, 06:28
judokan,

as per the second question, I tried picking numbers:

65 (sum of digits 11), remainder 2
92 (sum of digits 11), remainder 2
499 (sum of digits 22), remainder 4
6999 (sum of digits 33), remainder 6

how could it be A? Or do I miss something in the question?

Tks Para for pointing that out.

I just made up the question from memory.

I think n should be the digit should be divisible by 11, instead of multiciple of 11.

Tks
SVP
Joined: 29 Aug 2007
Posts: 2427
Re: DS: t divided by 7 [#permalink]

### Show Tags

08 Sep 2008, 09:19
judokan wrote:
(1) t = 7k + 6 (where k is integer)
t^2 + 5t +6
= 49k^2 + 14k + 36 + 35k + 30 + 6
= 49k^2 + 14k + 72
(the first two terms are multiple of 7)
so the reminder is equal to the remainder when 72 divided by 7, i.e. 2
(1) is sufficent

(2) t^2 = 7i +1 (where k is integer)
t^2 + 5t +6
= 7i + 1 + 5t + 6
= 7i + 7 + 5t
(the first two terms are multiple of 7)
so the reminder is equal to the remainder when 5t divided by 7

Now we try to find out the remainder when 5t divided by 7:
when i = 0, t^2 = 1, t = 1, remainder of t when divided by 7 = 1
when i = 5, t^2 = 36, t = 6, remainder of t when divided by 7 = 6
so, it give different results.
(2) alone is not suff.

Ans is A

1: agree with above
2: t could be1 or 6 or 8 and so on. r is different for t = 1, t = 6 and t = 8.
so nsf.

So A.

--== 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.

_________________

Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html

GT

Re: DS: t divided by 7   [#permalink] 08 Sep 2008, 09:19

Go to page   Previous    1   2   [ 24 posts ]

Display posts from previous: Sort by