It is currently 11 Dec 2017, 20:00

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

product of 8

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Intern
Intern
avatar
Joined: 13 Apr 2009
Posts: 12

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

product of 8 [#permalink]

Show Tags

New post 04 May 2009, 02:26
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Attachment:
33.png
33.png [ 27.2 KiB | Viewed 963 times ]

can anyone explain this?

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

Current Student
avatar
Joined: 13 May 2008
Posts: 141

Kudos [?]: 25 [0], given: 6

Schools: LBS
Re: product of 8 [#permalink]

Show Tags

New post 04 May 2009, 03:37
LOL.. I still remember this qs.. look break down the first 8 integers (actually 7 cuz, 1 is useless).. so u get
2x3x4x5x6x7x8 = (2^7) x (3^2) x 7 x 5... okay. do that its good for practice. Now since a^n is a factor of the product of these numbers, you can get deduce 'a' if u know 'n'... when n=6, it means a^6, so can u get one of the numbers to become (any #)^6, well turns out you can do that with '2' which is therefore your 'a' meaning the answer is B.

Kudos [?]: 25 [0], given: 6

Intern
Intern
avatar
Joined: 13 Apr 2009
Posts: 12

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

Re: product of 8 [#permalink]

Show Tags

New post 04 May 2009, 04:01
Thanks!
So i guess if st2 was one of the following : n=3 or n=4 or n=5 we would still get B as the right answer
cause the only opition a=2
but if st2 was n=2 it would have been E cause a=2 or a=3
right?

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

Current Student
avatar
Joined: 13 May 2008
Posts: 141

Kudos [?]: 25 [0], given: 6

Schools: LBS
Re: product of 8 [#permalink]

Show Tags

New post 04 May 2009, 04:07
aharonm wrote:
Thanks!
So i guess if st2 was one of the following : n=3 or n=4 or n=5 we would still get B as the right answer
cause the only opition a=2
but if st2 was n=2 it would have been E cause a=2 or a=3
right?



Actually if St2 was n=2, St1 would come into play and suggest that a=8 which would mean C.
If n=3, or n=4 or n=5 B would still be the right answer but in each case 'a' would be different, but even so St2 would be alone sufficient.

still I am not very sure with the possibilities u outlined.. do the math and check, maybe i did something wrong

Kudos [?]: 25 [0], given: 6

Intern
Intern
avatar
Joined: 13 Apr 2009
Posts: 12

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

Re: product of 8 [#permalink]

Show Tags

New post 04 May 2009, 04:17
why would a be different if n=3 n=4 or n=5?

it is still has to be a=2 because our product is (2^7) x (3^2) x 7 x 5 and the power of "2" is the only one above "2"

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

Expert Post
GMAT Tutor
avatar
S
Joined: 24 Jun 2008
Posts: 1347

Kudos [?]: 2039 [0], given: 6

Re: product of 8 [#permalink]

Show Tags

New post 04 May 2009, 06:51
aharonm wrote:
Thanks!
So i guess if st2 was one of the following : n=3 or n=4 or n=5 we would still get B as the right answer
cause the only opition a=2
but if st2 was n=2 it would have been E cause a=2 or a=3
right?


That's not quite right:

8! = (2^7)(3^2)(5^1)(7^1)

If n=6, 5 or 4, then a must be 2. If, however, n=3, then we have two possible values for a. a could again certainly be equal to 2, but a could also be equal to 4, since 4^3 = (2^2)^3 = 2^6, which is a divisor of 8!. If n = 2, there are quite a few possibilities: a could be 2, 3, 4, 6, 8, 12 or 24.

Of course as soon as you combine the statements, knowing that a is positive, you can definitely solve for a without even reading the rest of the information in the question. That's an immediate clue that C won't likely be the answer here - why would they bother including the information about 8! if it wasn't important in the solution of the problem?
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Kudos [?]: 2039 [0], given: 6

Manager
Manager
User avatar
Joined: 14 Nov 2008
Posts: 195

Kudos [?]: 132 [0], given: 3

Schools: Stanford...Wait, I will come!!!
Re: product of 8 [#permalink]

Show Tags

New post 05 May 2009, 00:21
Yeah, You are correct.
As our number is (2^7) x (3^2) x 7 x 5
So, if n> 2, we have only one number ..which is 2.
But if it is 2, then we have options 2&3.

aharonm wrote:
why would a be different if n=3 n=4 or n=5?

it is still has to be a=2 because our product is (2^7) x (3^2) x 7 x 5 and the power of "2" is the only one above "2"

Kudos [?]: 132 [0], given: 3

Senior Manager
Senior Manager
User avatar
Joined: 07 Jan 2008
Posts: 398

Kudos [?]: 311 [0], given: 0

Re: product of 8 [#permalink]

Show Tags

New post 05 May 2009, 05:31
Stm1:
a^n = 64 = 8^2=4^3=2^6
While 8! = (2^7) x (3^2) x 5 x 7 = (8^2)x(2) x (3^2) x 5 x 7 = (4^3)x(2) x (3^2) x 5 x 7 = (2^6)x(2) x (3^2) x 5 x 7
---> Insufficient!

Stm2:
n=6 ==> Only 2^6 meets the requirement (Because 8! is multiple of a^n) ==> Sufficient.

Kudos [?]: 311 [0], given: 0

Re: product of 8   [#permalink] 05 May 2009, 05:31
Display posts from previous: Sort by

product of 8

  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®.