NEW HERE? LEARN MORE
closeclose
Last visit was: 23 Apr 2024, 17:07 It is currently 23 Apr 2024, 17:07
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

From the word TRAMPLE 4 letters are taken. What is the

User avatar
BumblebeeMan
Intern
Intern
Joined: 05 Oct 2005
Posts: 39
Own Kudos [?]: 5 [0]
Given Kudos: 0
Send PM
From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Oct 2005, 04:45
From the word TRAMPLE 4 letters are taken. What is the probability that the word TRAM is arranged?

A. 1/2
B. 1/3
C. 1/7
D. 1/28
E. 1/35

I believe that all of these choices are incorrect. The correct answer should be 1/840.

If a word is arranged, then order matters, and we need to find the permutation instead of the combination. In this case, the probability of the word TRAM being arranged should be:

1/P(7,4)

P(7,4) = 7!/(7-4)! = 7!/3! = 7 x 6 x5 x 4 = 840

Thus the answer should be 1/840.

What do you guys think?



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
User avatar
krisrini
Manager
Manager
Joined: 15 Apr 2005
Posts: 159
Own Kudos [?]: 32 [0]
Given Kudos: 0
Location: India, Chennai
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Oct 2005, 04:51
I am no expert in Probablity. But I think 1/840 is correct.

Here is my working.

The probablity of choosing T is 1/7
The probablity of choosing R is 1/6
The probablity of choosing A is 1/5
The probablity of choosing M is 1/4

Hence (1/7)*(1/6)*(1/5)*(1/4) = 1/840
User avatar
BumblebeeMan
Intern
Intern
Joined: 05 Oct 2005
Posts: 39
Own Kudos [?]: 5 [0]
Given Kudos: 0
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Oct 2005, 04:53
krisrini wrote:
I am no expert in Probablity. But I think 1/840 is correct.

Here is my working.

The probablity of choosing T is 1/7
The probablity of choosing R is 1/6
The probablity of choosing A is 1/5
The probablity of choosing M is 1/4

Hence (1/7)*(1/6)*(1/5)*(1/4) = 1/840


I agree with you. However, the answer in the question collection takes that number and multiplies by 24 (incorrectly, in my opinion) to reach an answer of 1/35.
User avatar
christoph
Director
Director
Joined: 30 Sep 2004
Posts: 687
Own Kudos [?]: 1448 [0]
Given Kudos: 0
Location: Germany
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Oct 2005, 05:29
BumblebeeMan wrote:
krisrini wrote:
I am no expert in Probablity. But I think 1/840 is correct.

Here is my working.

The probablity of choosing T is 1/7
The probablity of choosing R is 1/6
The probablity of choosing A is 1/5
The probablity of choosing M is 1/4

Hence (1/7)*(1/6)*(1/5)*(1/4) = 1/840


I agree with you. However, the answer in the question collection takes that number and multiplies by 24 (incorrectly, in my opinion) to reach an answer of 1/35.


but there are two steps. firstly the letters are taken out and then the letters are arranged. that means 4 letters from 7 is 7c4 is 35. then 4 letters form 4, namely RAMT, is 4c4 is 1. now the 4 letters RAMT have to be arranged so that the word TRAM comes up. there is only 1 way to do so. so its 1/35...
User avatar
BumblebeeMan
Intern
Intern
Joined: 05 Oct 2005
Posts: 39
Own Kudos [?]: 5 [0]
Given Kudos: 0
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Oct 2005, 05:43
Quote:
but there are two steps. firstly the letters are taken out and then the letters are arranged. that means 4 letters from 7 is 7c4 is 35. then 4 letters form 4, namely RAMT, is 4c4 is 1. now the 4 letters RAMT have to be arranged so that the word TRAM comes up. there is only 1 way to do so. so its 1/35...


I disagree. The letters can be selected using 7c4 (which equals 35). However, you then have to multply 35 by the number of ways in which the letters can be arranged, which is 4!

35 x 4! = 840
User avatar
christoph
Director
Director
Joined: 30 Sep 2004
Posts: 687
Own Kudos [?]: 1448 [0]
Given Kudos: 0
Location: Germany
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Oct 2005, 05:57
BumblebeeMan wrote:
Quote:
but there are two steps. firstly the letters are taken out and then the letters are arranged. that means 4 letters from 7 is 7c4 is 35. then 4 letters form 4, namely RAMT, is 4c4 is 1. now the 4 letters RAMT have to be arranged so that the word TRAM comes up. there is only 1 way to do so. so its 1/35...


I disagree. The letters can be selected using 7c4 (which equals 35). However, you then have to multply 35 by the number of ways in which the letters can be arranged, which is 4!

35 x 4! = 840


hm? you are right :?
User avatar
dil66
Intern
Intern
Joined: 25 Jun 2005
Posts: 12
Own Kudos [?]: 3 [0]
Given Kudos: 0
Location: Bay Area, CA
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   08 Nov 2005, 19:35
BumblebeeMan wrote:
I disagree. The letters can be selected using 7c4 (which equals 35). However, you then have to multply 35 by the number of ways in which the letters can be arranged, which is 4!

35 x 4! = 840


There are 35 ways to select 4 letters from 7 letters. However, there is exactly one permutation of 4 letters that we are picking (TRAM) among the 4! possibilities.

So solution is 1/35.
User avatar
rlevochkin
Manager
Manager
Joined: 03 Nov 2005
Posts: 149
Own Kudos [?]: 109 [0]
Given Kudos: 17
Location: Chicago, IL
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Nov 2005, 22:06
Well, since the order the letters are chosen matters, Possible number of outcomes is 7P4=840. P=FO/EO=1/840. I thought about it this way.
User avatar
rlevochkin
Manager
Manager
Joined: 03 Nov 2005
Posts: 149
Own Kudos [?]: 109 [0]
Given Kudos: 17
Location: Chicago, IL
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   25 Nov 2005, 22:12
dil66 wrote:
BumblebeeMan wrote:
I disagree. The letters can be selected using 7c4 (which equals 35). However, you then have to multply 35 by the number of ways in which the letters can be arranged, which is 4!

35 x 4! = 840


There are 35 ways to select 4 letters from 7 letters. However, there is exactly one permutation of 4 letters that we are picking (TRAM) among the 4! possibilities.

So solution is 1/35.


you can't find probability (Favorable number of outcomes/ possible number of outcomes) unless you have both numerator and denominator in either combination or permutation. if order matters in the numerator, so it does in the denominator. I think
User avatar
nakib77
Director
Director
Joined: 28 May 2005
Posts: 986
Own Kudos [?]: 3460 [0]
Given Kudos: 0
Location: Dhaka
Send PM
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink] New post   26 Nov 2005, 00:14
it should be 1/7P4 = 1/840

answer choices are not correct.



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: From the word TRAMPLE 4 letters are taken. What is the [#permalink]
26 Nov 2005, 00:14
Moderator:
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions