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

It is currently 15 Apr 2014, 20:38

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

Was revising the questions I got from my prep classes and

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
User avatar
Joined: 02 Jan 2007
Posts: 211
Followers: 2

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

GMAT Tests User
Was revising the questions I got from my prep classes and [#permalink] New post 24 Apr 2007, 15:01
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Was revising the questions I got from my prep classes and this one came up that doesnt make sense to me....

How many different ways are there to select 2 cards from a standard deck of cards AND obtain 2 jacks?

There are no answer choices, just an OA which I'll post after you've had the kind of fun I had with this one :devil
Kaplan Promo CodeKnewton GMAT Discount CodesGMAT Pill GMAT Discount Codes
Current Student
User avatar
Joined: 22 Apr 2007
Posts: 1097
Followers: 5

Kudos [?]: 21 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 15:57
Okay, I am sure that I am solving it wrong. Anyway,

There are only 4 ways to pick a jack .. then only 3 ways to pick the other one. So, is the answer 12?

Edit: Well my answer seems too simple. Maybe I haven't understood the problem (Darn, that's not a good sign :-) ). riverripper, can you please elaborate on your solution?

Last edited by mNeo on 24 Apr 2007, 16:57, edited 3 times in total.
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 10 Apr 2007
Posts: 4320
Location: Back in Chicago, IL
Schools: Kellogg Alum: Class of 2010
Followers: 74

Kudos [?]: 688 [0], given: 5

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 16:12
Two ways to doing this...the easy way and the right way. Since you dont get style points the easiest way on this particular on on the for you may be to write out each option and count them out. Its easy when you only use 4 jacks, if it was a picking out two face cards it would be time consuming this way. If you can't think of the right math do whatever works.

The right way is to say there are 4 jacks, since you need to make a pair and one can't pair with itself you start with N-1. Then continue on N-2 until you reach N-N. Sum up the results (N-1)+(N-2)+(N-3)..+..(N-N) = X

So N=4
4-1 = 3
4-2 = 2
4-3 = 1
4-4 = 0

So for this there are 6 options. If it was 5 then there are 10. 6 would be 15...and so on.

Hope my crazy thinking doesnt confuse you.
Current Student
User avatar
Joined: 22 Apr 2007
Posts: 1097
Followers: 5

Kudos [?]: 21 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 16:58
up

riverripper, can you please elaborate on your solution? And perhaps explain the question too (As it seems that I misunderstood the question)
Intern
Intern
Joined: 24 Apr 2007
Posts: 9
Followers: 0

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

my answer [#permalink] New post 24 Apr 2007, 17:03
hi all,

it says how many different ways are there to pick 2 cards from a deck and end up with two jacks. so basically the number of ways to pick 2 jacks is all that matters because it is a subset of the number of ways to pick 2 cards from 52. And since it is the number of ways, i assume that order does matter, because if you pick jack of spades first, then jack of hearts second, that's a different way compared to the alternative. Then the formula should be:

4P2 4! / (4-2)! = 12
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5099
Location: Singapore
Followers: 15

Kudos [?]: 120 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 18:01
There are jack of hearts, spades, diamonds and something (I can't recall, I don't play cards)

ANyway, there should be 4 jacks in a deck of cards.

The number of ways to pick 2 jacks from these 4 = 4C2.
Current Student
User avatar
Joined: 22 Apr 2007
Posts: 1097
Followers: 5

Kudos [?]: 21 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 19:10
I think that the way of picking a heart and spade is different from the way of picking a spade and then a heart. Point is, it should be 4P2, not 4C2 in my opinion
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5099
Location: Singapore
Followers: 15

Kudos [?]: 120 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 19:16
mNeo wrote:
I think that the way of picking a heart and spade is different from the way of picking a spade and then a heart. Point is, it should be 4P2, not 4C2 in my opinion


Permutation considers order you pick the card. It doesn't matter if you pick a spade first then a heart or vice versa because you still end up with a jack of spade and a jack of heart. Combination should be used.
Current Student
User avatar
Joined: 22 Apr 2007
Posts: 1097
Followers: 5

Kudos [?]: 21 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 19:19
I understand that. But the question is "How many different ways are there to select 2 cards"

Isn't the way of choosing heart + spades different from the way of choosing spades + heart? I know that the end result is the same, though.

ps. Look at the post by jayt696969. I think I agree with his opinion
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5099
Location: Singapore
Followers: 15

Kudos [?]: 120 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 19:26
mNeo wrote:
I understand that. But the question is "How many different ways are there to select 2 cards"

Isn't the way of choosing heart + spades different from the way of choosing spades + heart? I know that the end result is the same, though.

ps. Look at the post by jayt696969. I think I agree with his opinion


I don't think I agree with that statement. It's like asking how many ways to pair up jack and jane in a two people team from a pool of four people: jack, jane, john and paul. If your argument is true, then the number of ways to pair up jack and jane is 2 -> (jack,jane) and (jane,jack). We know that's not true because that's really just 1 group. Same for the cards, is there any different in (spade,heart) and (heart,spade)? It's really just 1 group.
Senior Manager
Senior Manager
User avatar
Joined: 28 Aug 2006
Posts: 302
Followers: 10

Kudos [?]: 65 [0], given: 0

GMAT Tests User
 [#permalink] New post 24 Apr 2007, 21:57
It must be 4C2

Choosing Spade Jack+ Club Jack is same as Choosing Club Jack + Spade Jack
_________________

Averages Accelerated:Guide to solve Averages Quickly(with 10 practice problems)

Manager
Manager
User avatar
Joined: 02 Jan 2007
Posts: 211
Followers: 2

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

GMAT Tests User
 [#permalink] New post 25 Apr 2007, 04:11
ywilfred wrote:
There are jack of hearts, spades, diamonds and something (I can't recall, I don't play cards)

ANyway, there should be 4 jacks in a deck of cards.

The number of ways to pick 2 jacks from these 4 = 4C2.

Great work ywilfred!
That's the OA & OE :)

I thought it would be 52C2 :(
Obviosly that 52 is just a distraction that only seems to have distracted me :P
Manager
Manager
User avatar
Joined: 02 Jan 2007
Posts: 211
Followers: 2

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

GMAT Tests User
 [#permalink] New post 25 Apr 2007, 04:20
riverripper wrote:
So for this there are 6 options. If it was 5 then there are 10. 6 would be 15...and so on.

Hope my crazy thinking doesnt confuse you.

I don't know how you did it riverripper but your solution works!
I cross-checked your results for 5 Jacks & 6 Jacks using ywilfred's method and your method worked there too! :shock:

Easy way and the right way... i got to remember that :wink:
  [#permalink] 25 Apr 2007, 04:20
    Similar topics Author Replies Last post
Similar
Topics:
New posts 1 ask me questions . I got 760 in GMAT . I am from ShangHai darren 2 04 Feb 2008, 08:14
New posts 3 Experts publish their posts in the topic I am from shanghai and got 760 in Gmat. ask me questions darren 7 04 Feb 2008, 08:21
New posts Question Regarding Advice from a prep class instructor ca_gold 5 12 May 2008, 06:52
This topic is locked, you cannot edit posts or make further replies. New I got this on my GMAT Prep Co-ordinate DS_GMATPrep.PNG gmatpapa 1 27 Apr 2011, 09:51
New posts 20 A bunch of CR questions I got from a local GMAT club 700 GetThisDone 4 28 Apr 2012, 19:56
Display posts from previous: Sort by

Was revising the questions I got from my prep classes and

  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®.