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

It is currently 03 Aug 2015, 12:33
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

GMAT Prep - Combination Problem

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Intern
Intern
avatar
Joined: 25 Aug 2006
Posts: 25
Followers: 0

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

GMAT Prep - Combination Problem [#permalink] New post 29 Aug 2006, 15:20
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Can someone please tell me how they got 18,278 as an answer - see attached image of the problem.

AP
Attachments

File comment: Combinatoin Problem
gmatprep_problem10jpg.jpg
gmatprep_problem10jpg.jpg [ 38.44 KiB | Viewed 518 times ]

Manager
Manager
avatar
Joined: 26 Aug 2006
Posts: 67
Location: BeanTown
Followers: 1

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

 [#permalink] New post 29 Aug 2006, 17:59
1) possibilities for one letter - 26
2) possibilities for two letters - 26*26 = 676
3) possibilities for three letters - 26*26*26 = 17576

Total possibilities = 26+676+17576 = 18278
Manager
Manager
avatar
Joined: 20 Mar 2006
Posts: 200
Followers: 1

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

 [#permalink] New post 29 Aug 2006, 20:57
#of ways of selecting 1 digit code = 26
#of ways of selecting 2 digit code = 26^2(since digits can be repeated)
#of ways of selecting 3 digit code = 26^3(since digits can be repeated)

Total # of ways= 26+26^2+26^3
=26(1+26+26^2)
=26(703)
=18278

Hence E

Heman
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5240
Followers: 23

Kudos [?]: 200 [0], given: 0

 [#permalink] New post 30 Aug 2006, 00:52
Same method. Trick to this one is the to read the problem carefully. It says that the letters CAN be repeated. I think your answer choice would be something like 26+ (26*25) + (26*25*24), which is correct only if the letters CANNOT be repeated.
  [#permalink] 30 Aug 2006, 00:52
Display posts from previous: Sort by

GMAT Prep - Combination Problem

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.