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

It is currently 31 Aug 2015, 01:00
GMAT Club Tests

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 an integer n is to be chosen at random from the integers

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
User avatar
Joined: 08 Jun 2004
Posts: 498
Location: Europe
Followers: 1

Kudos [?]: 27 [0], given: 0

If an integer n is to be chosen at random from the integers [#permalink] New post 25 Apr 2006, 11:24
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If an integer n is to be chosen at random from the integers 1 to 96, inclusive, what is the probability that n(n + 1)(n + 2) will be divisible by 8?

A. 1/4
B. 3/8
C. 1/2
D. 5/8
E. 3/4

Please explain your answer.
Director
Director
User avatar
Joined: 04 Jan 2006
Posts: 925
Followers: 1

Kudos [?]: 19 [0], given: 0

 [#permalink] New post 25 Apr 2006, 18:23
1/2?

Probabiltity that n is chosen even.. is 1/2..
as long as n is even, the product is divisible by 8?
Manager
Manager
avatar
Joined: 21 Mar 2006
Posts: 89
Followers: 1

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

 [#permalink] New post 25 Apr 2006, 18:45
Can someone shed some light on this one and provide a detailed explanation?
Director
Director
User avatar
Joined: 04 Jan 2006
Posts: 925
Followers: 1

Kudos [?]: 19 [0], given: 0

 [#permalink] New post 25 Apr 2006, 20:10
if n is even, n*n+1*n+2 is always going to be divisible by 8
example:
n = 2,n+1=3,n+2 = 4
since we have two consecutive even numbers in this, the product will be always divisible by 8..

try out numbers

4,5,6
6,7,8
8,9,10
14,15,16
18,19,20

2 will always be repeated three times..

so then the probability to get n as even would be :
48/96(half of them are even)
1/2

Does that help? maybe someone else can explain better
Director
Director
User avatar
Joined: 04 Jan 2006
Posts: 925
Followers: 1

Kudos [?]: 19 [0], given: 0

 [#permalink] New post 25 Apr 2006, 20:18
ARGHHHHHHHHH while explaining to u i realised i was wrong..

p(n is even) or p(n+1 is div by 8,i.e n is odd , but n = 7,15 etc..)

1/2 + 1/8 = 5/8..

Is that OA?
Senior Manager
Senior Manager
User avatar
Joined: 08 Jun 2004
Posts: 498
Location: Europe
Followers: 1

Kudos [?]: 27 [0], given: 0

 [#permalink] New post 26 Apr 2006, 09:49
willget800 wrote:
ARGHHHHHHHHH while explaining to u i realised i was wrong..

p(n is even) or p(n+1 is div by 8,i.e n is odd , but n = 7,15 etc..)

1/2 + 1/8 = 5/8..

Is that OA?


Please elaborate your answer with '1/8' why do you use it?
Intern
Intern
avatar
Joined: 12 Mar 2006
Posts: 26
Followers: 0

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

 [#permalink] New post 26 Apr 2006, 10:27
5/8

Even: 48 possibilities
Odd: every 4 hits, so 48/4 = 12

Probability = 48+12 / 96

Ans: 5/8
Senior Manager
Senior Manager
User avatar
Joined: 08 Jun 2004
Posts: 498
Location: Europe
Followers: 1

Kudos [?]: 27 [0], given: 0

 [#permalink] New post 30 Apr 2006, 03:19
OA is 'D', but can anybody explain the fast solution?
VP
VP
avatar
Joined: 21 Sep 2003
Posts: 1065
Location: USA
Followers: 3

Kudos [?]: 43 [0], given: 0

 [#permalink] New post 30 Apr 2006, 05:25
M8 wrote:
OA is 'D', but can anybody explain the fast solution?


Here is a link to the previous discussion:
http://www.gmatclub.com/phpbb/viewtopic.php?p=189499
_________________

"To dream anything that you want to dream, that is the beauty of the human mind. To do anything that you want to do, that is the strength of the human will. To trust yourself, to test your limits, that is the courage to succeed."

- Bernard Edmonds

  [#permalink] 30 Apr 2006, 05:25
Display posts from previous: Sort by

If an integer n is to be chosen at random from the integers

  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®.