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

It is currently 10 Jul 2014, 13:52

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

Judges will select 5 finalists from the 7 contestant

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
VP
VP
avatar
Joined: 30 Sep 2004
Posts: 1493
Location: Germany
Followers: 4

Kudos [?]: 34 [1] , given: 0

GMAT Tests User
Judges will select 5 finalists from the 7 contestant [#permalink] New post 09 Apr 2005, 00:53
1
This post received
KUDOS
4
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

41% (12:54) correct 58% (01:12) wrong based on 212 sessions
Judges will select 5 finalists from the 7 contestants entered in a singing competition. The judges will then rank the contestants and award prizes to the 3 highest ranked contestants: a blue ribbon for first place, a red ribbon for second place, and a yellow ribbon for third place. How many different arrangements of prize-winners are possible?

A. 10
B. 21
C. 210
D. 420
E. 1,260
[Reveal] Spoiler: OA

_________________

If your mind can conceive it and your heart can believe it, have faith that you can achieve it.

Director
Director
avatar
Joined: 18 Feb 2005
Posts: 674
Followers: 1

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

GMAT Tests User
Re: PS-combinations and permutations: finalists [#permalink] New post 10 Apr 2005, 18:19
MA wrote:
E. 1,260 = (7C5) (5P3) = 21x60


Thats what I thought


slect 5 guys from 7 then arrange 3 out of 5

===>> 7C5*5P3 = 1260
4 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 15 Mar 2005
Posts: 425
Location: Phoenix
Followers: 1

Kudos [?]: 9 [4] , given: 0

GMAT Tests User
Re: PS-combinations and permutations: finalists [#permalink] New post 11 Apr 2005, 14:32
4
This post received
KUDOS
Zem wrote:
Judges will select 5 finalists from the 7 contestants entered in a
singing competition. The judges will then rank the contestants
and award prizes to the 3 highest ranked contestants: a blue
ribbon for first place, a red ribbon for second place, and a
<a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=22&k=yellow%20ribbon" onmouseover="window.status='yellow ribbon'; return true;" onmouseout="window.status=''; return true;">yellow ribbon</a> for third place. How many different arrangements
of prize-winners are possible?

A 10
B 21
C 210
D 420
E 1,260


Let me pitch in here with some of my views. Let me know if you agree/disagree or want to add/subtract to it.

There are two ways of looking at this problem -

1. Going strictly by the words of the problem.
2. Going by what they do in the problem situation.

Lets discuss them one by one.

1. The problem asks "How many different arrangements of prize-winners are possible". Now its obvious that there are three prize winners out of a total of 7 contestents. And arrangement means Permutation. Going by that, the answer is simply P(7,3) = 7!/4! = 5x6x7 = 210.

2. They do the math in a little more complex way. They choose and choose and choose within the choice. Please note that these values differ.

Choosing A+B from A+B+C and then choosing A from A+B.

[C(A+B+C, A+B) x C(A+B, A)] = (A+B+C)!/A! B! C! ..........eqn (P)

AND

Choosing A from A+B+C.
[C(A+B+C, A)] = (A+B+C)!/A! (B+C)! .............................eqn (Q)

While the objective is the same in both cases, results are different. The reason is important:

It is the ways in which we make the selection. And the ways in which the selection is made isn't universally unique - it depends on the sample set and the sampled size.

This looks a little difficult to digest - especially since we've almost learnt to believe that the number of ways of making a selection are universally unique (and considering how the laws of probability are linked to them, the probability is also constant). This however isn't true. Consider this:

We have a box containing 5 red and 5 black socks. We take out two socks. What is the probability that both of them are of the same color?

1. Take them out one after another, without replacing.
2. Take 2 out at a time.

Bet the answers are different.

Let me give a simpler example, not of probability but of permutations and combinations.

In how many ways can be take 2 fruits out of a basket of 5 fruits.
1. Taking out both together, or
2. Taking out one after another, without replacement.

The first is C(5, 2) = 10.
The second is 5x4 = 20.

Its important to note in this problem that the second case implicitly considers permutation, instead of combination.

So in the question posed, we have this difference.

When we consider the top 3 prize winners only, we ignore completely the 4th, 5th 6th and 7th rankers.

However when we select 5 and then select 3 of them, in the first count, we select 5, ignoring 2 and then select 3, ignoring 2 more, and then make a permutation of those 3.

In the problem presented, the elements 4th and 5th because are present in the consideration again (after the first selection), the number of ways of ordering increases.

Thus in case (2), we have
C(7, 5) * 5*4*3 = 21*60 = 1260.

As one more illustration, consider equations P and Q. The difference in choosing between 3 directly and 3, 2, 2 format is the difference between (2+2)! and 2! 2! or 24/6 = 6 times.

This is the same as the ratio between our two answers - 1260 and 210.

Hope this helps.
_________________

Who says elephants can't dance?

Director
Director
User avatar
Joined: 31 Aug 2004
Posts: 609
Followers: 2

Kudos [?]: 15 [0], given: 0

GMAT Tests User
Judges [#permalink] New post 11 Apr 2005, 15:17
I finally agree with Christoph.
We do not care the selection from 5 out of 7 cause the only important stuff is these 3 awarded positions. There are redundancies from these 7C5 ways because lots of these arangements can lead to the same award list...

So the answer is 7 to select the 1sy one, then 6 for the second place and then 5 for the third one, 210 being my final choice.
3 KUDOS received
Manager
Manager
avatar
Joined: 22 Jan 2012
Posts: 90
Location: India
Concentration: General Management, Technology
GMAT 1: Q39 V29
GPA: 3.3
WE: Engineering (Consulting)
Followers: 5

Kudos [?]: 41 [3] , given: 7

Re: Judges will select 5 finalists from the 7 contestants [#permalink] New post 18 Mar 2012, 22:24
3
This post received
KUDOS
Simple Answer :

First Select 5 from 7 contestants and then select top 3 from those 5 =

7C5*5C3 = 42 * 5 = 210
_________________

Press +1 Kudos rather than saying thanks
which is more helpful infact..

Ill be posting good questions as many as I can...

Towards Success

Expert Post
3 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [3] , given: 2537

Re: Judges will select 5 finalists [#permalink] New post 20 Mar 2012, 12:35
3
This post received
KUDOS
Expert's post
Zem wrote:
Judges will select 5 finalists from the 7 contestants entered in a singing competition. The judges will then rank the contestants and award prizes to the 3 highest ranked contestants: a blue ribbon for first place, a red ribbon for second place, and a yellow ribbon for third place. How many different arrangements of prize-winners are possible?

A. 10
B. 21
C. 210
D. 420
E. 1,260


Intermediary step of selecting 5 finalists first is just to confuse us: any group of 5 is equally likely to be selected, so we can skip this part and directly calculate ways to arrange 3 contestants out of 7: C^3_7*3!=210.

Answer: C.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
avatar
Joined: 14 Apr 2012
Posts: 7
Followers: 0

Kudos [?]: 0 [0], given: 35

Re: Judges will select 5 finalists [#permalink] New post 26 Apr 2012, 12:28
Bunuel, Would you go into details with your explanation, plz??
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [1] , given: 2537

Re: Judges will select 5 finalists [#permalink] New post 26 Apr 2012, 21:47
1
This post received
KUDOS
Expert's post
mofasser08 wrote:
Bunuel, Would you go into details with your explanation, plz??


Ask yourself, why should # of arrangement be different for the case with intermediary step and for the case without it?

Or, HOW can # of arrangements of 3 people out 7 (with or without intermediary step) be more than P^3_7 (C^3_7*3!=210)? I mean what different arrangement can there possibly be which is not counted in P^3_7? Or which arrangement there won't be because of that intermediary step?
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
User avatar
Joined: 23 Oct 2010
Posts: 383
Location: Azerbaijan
Concentration: Finance
GMAT 1: 690 Q47 V38
Followers: 11

Kudos [?]: 119 [0], given: 72

GMAT ToolKit User
Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 26 Apr 2012, 23:38
hm I also got the answer C

7C5 * 5C3=21*10=210
_________________

Happy are those who dream dreams and are ready to pay the price to make them come true

Intern
Intern
avatar
Joined: 14 Apr 2012
Posts: 7
Followers: 0

Kudos [?]: 0 [0], given: 35

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 01 May 2012, 12:19
Bunuel, what If the question were like :-Judges, in the first round, will select 5 finalists (on the basis of any specific criteria)from the 7 contestants entered in a singing competition. Then in the 2nd round the judges will rank the contestants and award prizes to the 3 highest ranked contestants: a blue ribbon for first place, a red ribbon for second place, and a yellow ribbon for third place. How many different arrangements of prize-winners are possible?

Would it be the ans:(7C5)* (5P3) = 21x60=1260 ?
1 KUDOS received
Manager
Manager
avatar
Joined: 09 Apr 2012
Posts: 61
Followers: 0

Kudos [?]: 14 [1] , given: 25

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 08 Feb 2013, 14:33
1
This post received
KUDOS
Can someone point me if there is anything wrong with this approach? (I cannot understand why others did not choose this but rather choose a longer complex way.)

7 contestants, 3 unique prizes.
total number od ways in which the prizes can be distributed in 7P3=210.
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [0], given: 2537

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 09 Feb 2013, 01:11
Expert's post
nkimidi7y wrote:
Can someone point me if there is anything wrong with this approach? (I cannot understand why others did not choose this but rather choose a longer complex way.)

7 contestants, 3 unique prizes.
total number od ways in which the prizes can be distributed in 7P3=210.


There is nothing wrong with your approach. It's the same as in my posts above:
judges-will-select-5-finalists-from-the-7-contestant-15465.html?sid=898cc3a71745cbceb32fd2c429b1ee76#p1062007
judges-will-select-5-finalists-from-the-7-contestant-15465.html?sid=3884f074de011c5cac84969cf7767111#p1078994
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 28 Aug 2012
Posts: 53
Concentration: Operations, Marketing
GMAT 1: 510 Q36 V25
GPA: 4
WE: Information Technology (Other)
Followers: 0

Kudos [?]: 36 [0], given: 105

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 10 Feb 2013, 02:21
Bunuel ,
I went about this problem like this
Since they are asking for total no of arrangements , i did 7*6*5 =210 . 7 ppl can win 1st place,6 ppl can win 2nd place and 5 ppl can win third. Is this approach correct or would this work only for this situation ?
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [0], given: 2537

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 10 Feb 2013, 02:46
Expert's post
thinktank wrote:
Bunuel ,
I went about this problem like this
Since they are asking for total no of arrangements , i did 7*6*5 =210 . 7 ppl can win 1st place,6 ppl can win 2nd place and 5 ppl can win third. Is this approach correct or would this work only for this situation ?


Your approach is correct:
7 options for the first place;
6 options for the second place;
5 options for the third place.

Total 7*6*5=210.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
User avatar
Joined: 17 Dec 2012
Posts: 380
Location: India
Followers: 10

Kudos [?]: 144 [0], given: 9

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 06 May 2013, 02:41
christoph wrote:
Judges will select 5 finalists from the 7 contestants entered in a singing competition. The judges will then rank the contestants and award prizes to the 3 highest ranked contestants: a blue ribbon for first place, a red ribbon for second place, and a yellow ribbon for third place. How many different arrangements of prize-winners are possible?

A. 10
B. 21
C. 210
D. 420
E. 1,260


In my view, the answer cannot be 7P3. The reason is, when we select 3 prize winners, we expect that all the three are finalists in the group of prize winners. But this is not the case if we include those who are not finalists while considering the arrangement of prize winners.

The possible number of arrangement of prize winners is7C3 * 5P3.
_________________

Srinivasan Vaidyaraman
Sravna Test Prep
http://www.sravna.com/courses.php

Classroom Courses in Chennai

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [0], given: 2537

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 06 May 2013, 02:49
Expert's post
SravnaTestPrep wrote:
christoph wrote:
Judges will select 5 finalists from the 7 contestants entered in a singing competition. The judges will then rank the contestants and award prizes to the 3 highest ranked contestants: a blue ribbon for first place, a red ribbon for second place, and a yellow ribbon for third place. How many different arrangements of prize-winners are possible?

A. 10
B. 21
C. 210
D. 420
E. 1,260


In my view, the answer cannot be 7P3. The reason is, when we select 3 prize winners, we expect that all the three are finalists in the group of prize winners. But this is not the case if we include those who are not finalists while considering the arrangement of prize winners.

The possible number of arrangement of prize winners is7C3 * 5P3.


OA is C (210).

You can try smaller numbers and list all cases to check that your approach won't give the correct answer.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
User avatar
Joined: 17 Dec 2012
Posts: 380
Location: India
Followers: 10

Kudos [?]: 144 [0], given: 9

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 06 May 2013, 02:55
Bunuel wrote:
SravnaTestPrep wrote:
christoph wrote:
Judges will select 5 finalists from the 7 contestants entered in a singing competition. The judges will then rank the contestants and award prizes to the 3 highest ranked contestants: a blue ribbon for first place, a red ribbon for second place, and a yellow ribbon for third place. How many different arrangements of prize-winners are possible?

A. 10
B. 21
C. 210
D. 420
E. 1,260


In my view, the answer cannot be 7P3. The reason is, when we select 3 prize winners, we expect that all the three are finalists in the group of prize winners. But this is not the case if we include those who are not finalists while considering the arrangement of prize winners.


The possible number of arrangement of prize winners is7C3 * 5P3.


OA is C (210).

You can try smaller numbers and list all cases to check that your approach won't give the correct answer.


Then I think the OA is not correct. If the contestants are A, B, C, D, E, F and G and A, B, C, D, and E are finally selected how can F and G be among any list of prize winners?
_________________

Srinivasan Vaidyaraman
Sravna Test Prep
http://www.sravna.com/courses.php

Classroom Courses in Chennai

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [0], given: 2537

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 06 May 2013, 02:59
Expert's post
SravnaTestPrep wrote:
Bunuel wrote:
SravnaTestPrep wrote:

OA is C (210).

You can try smaller numbers and list all cases to check that your approach won't give the correct answer.


Then I think the OA is not correct. If the contestants are A, B, C, D, E, F and G and A, B, C, D, and E are finally selected how can F and G be among any list of prize winners?


OA is not wrong. Again, try to get the answer if it were 4 contestants with your approach and you'll see that your approach is not correct.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
User avatar
Joined: 17 Dec 2012
Posts: 380
Location: India
Followers: 10

Kudos [?]: 144 [0], given: 9

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 06 May 2013, 03:31
Quote:
OA is not wrong. Again, try to get the answer if it were 4 contestants with your approach and you'll see that your approach is not correct.


Four Contestants : A B C D

Three are selected. This can be done in 4 C 3 ways - ABC, ABD, BCD, ACD

Consider 2 prizes

The prize winners from the above four combination of finalists can each be arranged in 3P2 ways

The answer is 4C3 * 3P2

Each of the 4C3 ways are independent of one another and so the arrangements have to be considered independently. It will be a repetition only within the same combination. So the ranking AB in ABC is independent of the same ranking AB in ABD. So we will have the prize winners AB in ABC and the prize winners AB in ABD and so on.

Your approach is obviously wrong because non finalists cannot be considered as prize winners.
_________________

Srinivasan Vaidyaraman
Sravna Test Prep
http://www.sravna.com/courses.php

Classroom Courses in Chennai

Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18490
Followers: 3187

Kudos [?]: 21196 [1] , given: 2537

Re: Judges will select 5 finalists from the 7 contestant [#permalink] New post 06 May 2013, 05:18
1
This post received
KUDOS
Expert's post
SravnaTestPrep wrote:
Quote:
OA is not wrong. Again, try to get the answer if it were 4 contestants with your approach and you'll see that your approach is not correct.


Four Contestants : A B C D

Three are selected. This can be done in 4 C 3 ways - ABC, ABD, BCD, ACD

Consider 2 prizes

The prize winners from the above four combination of finalists can each be arranged in 3P2 ways

The answer is 4C3 * 3P2

Each of the 4C3 ways are independent of one another and so the arrangements have to be considered independently. It will be a repetition only within the same combination. So the ranking AB in ABC is independent of the same ranking AB in ABD. So we will have the prize winners AB in ABC and the prize winners AB in ABD and so on.

Your approach is obviously wrong because non finalists cannot be considered as prize winners.


That's not correct. Either you don't understand the question or the solutions.

Four Contestants : A B C D and 3 prizes. Possible cases:
ABC
ACB
BAC
BCA
CAB
CBA

ABD
ADB
BAD
BDA
DAB
DBA

ACD
ADC
CAD
CDA
DAC
DCA

BCD
BDC
CBD
CDB
DBC
DCB

Total of 24 cases.

My approach: P^3_4=4!=24 --> correct.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Re: Judges will select 5 finalists from the 7 contestant   [#permalink] 06 May 2013, 05:18
    Similar topics Author Replies Last post
Similar
Topics:
2011 finalists « Best Illusion of the Year Contest subhashghosh 1 27 May 2011, 03:24
Ben and Ann are among 7 contestants from which 4 tarek99 8 17 Mar 2008, 06:47
3 Ben and Ann are among 7 contestants from which 4 JCLEONES 2 08 Feb 2008, 11:50
Ben and Ann are among 7 contestants from which 4 lan583 3 07 Nov 2006, 12:16
Judges will select 5 finalists from the 7 contestants gayathri 14 17 Jan 2005, 13:39
Display posts from previous: Sort by

Judges will select 5 finalists from the 7 contestant

  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®.