Find all School-related info fast with the new School-Specific MBA Forum

It is currently 23 Oct 2014, 03:06

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If d is a positive factor and f is the product of the first

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 14 Nov 2005
Posts: 67
Followers: 1

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

If d is a positive factor and f is the product of the first [#permalink] New post 15 May 2006, 07:03
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions
If d is a positive factor and f is the product of the first 30 positve integers, what is the value of d?

1. 10^d is a factor of f
2. d > 6
Director
Director
avatar
Joined: 24 Oct 2005
Posts: 662
Location: London
Followers: 1

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

 [#permalink] New post 15 May 2006, 07:11
I go with C.

Statement 1 gives d = 3, 6, 7

Statement 2 gives d = a lot of nos.

Combining, d = 7

Last edited by remgeo on 15 May 2006, 08:03, edited 1 time in total.
Manager
Manager
avatar
Joined: 23 Jan 2006
Posts: 193
Followers: 1

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

 [#permalink] New post 15 May 2006, 07:18
My guess is C.

(1) f is a factor of 10, but 10^1, 10^2, 10^3.... are also factors of 10
INSUFF
(2) obviously insuff

together
in 30!, there are 3 factors that contain ten: 10:10*1, 20:10*2, 30:10*3, and 3 factors containing 5: 5, 15:5*3, 25:5*5. cobine each of those 5's with one of the many 2's in the factorization for another 4 10's, that makes 7 10's total. if d>6, d must be 7.
Director
Director
avatar
Joined: 16 Aug 2005
Posts: 950
Location: France
Followers: 1

Kudos [?]: 8 [0], given: 0

 [#permalink] New post 15 May 2006, 08:10
If d is a positive factor and f is the product of the first 30 positve integers, what is the value of d?

1. 10^d is a factor of f
2. d > 6

From (1), d can be = 0, 1, 2, 3..
Not sufficient

From (2),
Not sufficient as we do not know anything about d

Taking both together:
f = 30! and we have to check if that # can be divided by 10^7 or higher.

(5x2) x 10 x 20 x 30 x (15x6) x (25x4=100) would make 10^7 a factor.

Hence C
Manager
Manager
User avatar
Joined: 27 Jan 2006
Posts: 156
Location: Europe
Followers: 1

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

 [#permalink] New post 17 May 2006, 09:04
:?
What if the value of d is 8,9,10....?

f = 30! = 265252859812191000000000000000000

Sorry. I just calculated it by excel...

so IMO, 10^8, 10^9, 10^10...also possible...
_________________

Stay hungry, Stay foolish

CEO
CEO
User avatar
Joined: 20 Nov 2005
Posts: 2922
Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
Followers: 15

Kudos [?]: 82 [0], given: 0

 [#permalink] New post 17 May 2006, 09:40
jeunesis wrote:
:?
What if the value of d is 8,9,10....?

f = 30! = 265252859812191000000000000000000

Sorry. I just calculated it by excel...

so IMO, 10^8, 10^9, 10^10...also possible...


This is incorrect. There will be 7 zeros only. Thats how its calculated:

Numbers multiple of 5 = 5,15,25 = 3
Numbers multiple of 25 = 25 = 1
Numbers multiple of 10 = 10,20,30 = 3

So total zeros = 3+1+3 = 7

St1: d may be 1,2,3,4,5,6,7 : INSUFF
St2: d may be 6,7,....... and many more : INSUFF

Combined: d must be 7 : SUFF
So it must be C.
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

Manager
Manager
avatar
Joined: 13 Aug 2005
Posts: 136
Followers: 1

Kudos [?]: 1 [0], given: 0

 [#permalink] New post 17 May 2006, 20:32
I used the same approach as Dahiya, but stuck with 10^6.

When you counted 25 you counted it twice. Why?
Senior Manager
Senior Manager
avatar
Joined: 15 Mar 2005
Posts: 423
Location: Phoenix
Followers: 1

Kudos [?]: 9 [0], given: 0

 [#permalink] New post 18 May 2006, 00:16
Natalya Khimich wrote:
I used the same approach as Dahiya, but stuck with 10^6.

When you counted 25 you counted it twice. Why?


Thats because 25 = 5x5.

We compute 5s and 2s in the product to determine the number of zeroes the product would have. Typically since the number of twos are sufficient, we can make our lives easier by counting the number of 5s alone. And 5s are counted by counting in all the factors of 5s (5, 10, 15 etc) but counting extra for powers of 5, like 25, 125 and 625 (which have 2, 3 and 4 5s respectively).

Hope that helps.
_________________

Who says elephants can't dance?

  [#permalink] 18 May 2006, 00:16
    Similar topics Author Replies Last post
Similar
Topics:
22 Experts publish their posts in the topic If d is a positive integer and f is the product of the first enigma123 8 28 Jan 2012, 17:13
18 Experts publish their posts in the topic If d is a positive integer and f is the product of the first zoom 69 10 Sep 2005, 11:58
Experts publish their posts in the topic If D is a positive number and F is the product of the first netcaesar 1 25 Jan 2008, 10:41
If d is a positive integer and f is the product of the first TOUGH GUY 11 31 Jan 2007, 05:20
If d is a positive integer and f is the product of the first coffeeloverfreak 5 22 Sep 2005, 20:54
Display posts from previous: Sort by

If d is a positive factor and f is the product of the first

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.