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

 It is currently 07 Jul 2015, 20:26

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

If a code word is defined to be a sequence of different

Author Message
TAGS:
Senior Manager
Joined: 14 Jul 2005
Posts: 402
Followers: 1

Kudos [?]: 12 [0], given: 0

If a code word is defined to be a sequence of different [#permalink]  23 Aug 2006, 19:36
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?

A) 5 to 4
B) 3 to 2
C) 2 to 1
D) 5 to 1
E) 6 to 1
Senior Manager
Joined: 14 Aug 2006
Posts: 365
Followers: 1

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

different sequence of numbers imply that ABCDE is different from EDCBA

so using permutations:

10P5/10P4 = (10!/5! )/ (10!/6!) = 6 to 1

Manager
Joined: 20 Mar 2006
Posts: 200
Followers: 1

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

Re: PS - Ratio [#permalink]  23 Aug 2006, 20:14
gmatornot wrote:
If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?

A) 5 to 4
B) 3 to 2
C) 2 to 1
D) 5 to 1
E) 6 to 1

10c5 = Number of ways of selecting 5 letter code words
= 10*9*8*7*6/5!

10c4 = Number of ways of selecting 4 letter code words
= 10*9*8*7*/4!

@ This point i Divided 10c5/10c4 to get 6/5 which is not one of the answer choices.

So went back and saw that after selecting the 5 digit or 4 digit letter code we could arrange them differently

so Number of ways of selecting 5 letter words and arrangiing them=
10c5 * 5! = 10*9*8*7*6

so Number of ways of selecting 4 letter words and arrangiing them=
10c4 * 4! = 10*9*8*7

So required ratio = 6/1

What is the source of this ?

E

Heman
Manager
Joined: 20 Mar 2006
Posts: 200
Followers: 1

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

trivikram wrote:
(10C5*5!)/(10C4*4!) = 3/2

B it is

I believe this calculation comes out to 6/1

Heman
VP
Joined: 28 Mar 2006
Posts: 1383
Followers: 2

Kudos [?]: 20 [0], given: 0

heman wrote:
trivikram wrote:
(10C5*5!)/(10C4*4!) = 3/2

B it is

I believe this calculation comes out to 6/1

Heman

I do this types of mistakes all the time and screw myself up ....
Similar topics Replies Last post
Similar
Topics:
21 If a code word is defined to be a sequence of different 15 28 Jan 2012, 02:59
3 If a code word is defined to be a sequence of different 5 05 Sep 2010, 05:52
If a code word is defined to be a sequence of different 3 01 Jun 2008, 12:22
If a code word is defined to be a sequence of different 4 14 Apr 2008, 12:09
If a code word is defined to be a sequence of different 3 25 Apr 2006, 11:21
Display posts from previous: Sort by