NEW HERE? LEARN MORE
closeclose
Last visit was: 03 May 2024, 16:19 It is currently 03 May 2024, 16:19
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

I found this problem on the internet while trying to find

 1   2   
User avatar
nitinneha
Manager
Manager
Joined: 15 Nov 2006
Posts: 142
Own Kudos [?]: 460 [0]
Given Kudos: 0
Location: Ohio
Send PM
I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 11:02
I found this problem on the internet while trying to find some practice material:

Tom has 30 apples, 15 of them are bad.Steve has 30 oranges and 6 of them are bad. Both Tom and Steve have to put two apples and two oranges in a basket at random. What is the probability that the basket would have exactly two bad apples and two bad oranges?

I tried to solve it but looks like something is missing..........can someone help.



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
yuefei
Intern
Intern
Joined: 02 Aug 2007
Posts: 44
Own Kudos [?]: 202 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 11:06
P(T bad apples) = 2/15
P(S bad oranges) = 2/6

P = (2/15)*(2/6) = 4/90 = 2/45
User avatar
johnbaker
Intern
Intern
Joined: 25 Apr 2007
Posts: 19
Own Kudos [?]: 7 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 11:36
But don't you have to consider the probability of picking BAD one's only from the entire lot ?
User avatar
young_gun
Current Student
Joined: 31 Aug 2007
Posts: 283
Own Kudos [?]: 624 [0]
Given Kudos: 1
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 11:42
i'm getting 4/29, but I fear I'm wrong.
User avatar
KillerSquirrel
Director
Director
Joined: 08 Jun 2005
Posts: 523
Own Kudos [?]: 559 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   Updated on: 26 Oct 2007, 15:22
15/30*14/29 + 6/30*5/29 = 7/29 + 1/29 = 8/29

this is wrong - see followup posts

:)

Originally posted by KillerSquirrel on 26 Oct 2007, 12:13.
Last edited by KillerSquirrel on 26 Oct 2007, 15:22, edited 1 time in total.
User avatar
abiswas
Manager
Manager
Joined: 21 Feb 2007
Posts: 56
Own Kudos [?]: 90 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:15
I got 8/29 too like KS
User avatar
yuefei
Intern
Intern
Joined: 02 Aug 2007
Posts: 44
Own Kudos [?]: 202 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:25
Why do we add the probability of these two events? These are two mutually exclusive events, and we are looking for the probability of 1 event AND the other event.
User avatar
KillerSquirrel
Director
Director
Joined: 08 Jun 2005
Posts: 523
Own Kudos [?]: 559 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   Updated on: 26 Oct 2007, 15:21
yuefei wrote:
Why do we add the probability of these two events? These are two mutually exclusive events, and we are looking for the probability of 1 event AND the other event.


AND ---> multiply

:)

Originally posted by KillerSquirrel on 26 Oct 2007, 13:28.
Last edited by KillerSquirrel on 26 Oct 2007, 15:21, edited 1 time in total.
User avatar
yuefei
Intern
Intern
Joined: 02 Aug 2007
Posts: 44
Own Kudos [?]: 202 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:32
Well if you throw a dice twice, what is the probability that you throw six both times?
P = (1/6)*(1/6) = 1/36

What if the question had asked what is the probability of selecting 2 bad apples or 2 bad oranges? The result would have two scenarios, which would provide for p = p(1) + p(2). Thoughts?
User avatar
young_gun
Current Student
Joined: 31 Aug 2007
Posts: 283
Own Kudos [?]: 624 [0]
Given Kudos: 1
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:36
yuefei wrote:
Well if you throw a dice twice, what is the probability that you throw six both times?
P = (1/6)*(1/6) = 1/36

What if the question had asked what is the probability of selecting 2 bad apples or 2 bad oranges? The result would have two scenarios, which would provide for p = p(1) + p(2). Thoughts?


this is also tripping me up!
User avatar
KillerSquirrel
Director
Director
Joined: 08 Jun 2005
Posts: 523
Own Kudos [?]: 559 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:41
yuefei wrote:
Well if you throw a dice twice, what is the probability that you throw six both times?

P = (1/6)*(1/6) = 1/36

What if the question had asked what is the probability of selecting 2 bad apples or 2 bad oranges? The result would have two scenarios, which would provide for p = p(1) + p(2). Thoughts?


probability of selecting 2 bad apples or 2 bad oranges ?

21/60*14/59 ---> two bad apples

21/60*5/59 ---> two bad oranges

total

21/60*14/59+21/60*5/59 =

:)
User avatar
yuefei
Intern
Intern
Joined: 02 Aug 2007
Posts: 44
Own Kudos [?]: 202 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:46
KillerS, you're a machine!!
User avatar
KillerSquirrel
Director
Director
Joined: 08 Jun 2005
Posts: 523
Own Kudos [?]: 559 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 13:48
Does anyone has an OA here ? Or is this an academic debate ?

:wink:
User avatar
ggarr
Senior Manager
Senior Manager
Joined: 12 Jun 2006
Posts: 263
Own Kudos [?]: 692 [0]
Given Kudos: 1
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 14:40
OA here. I was thinking the answer is 7/841 (7/29*1/29)
User avatar
Fig
VP
VP
Joined: 01 May 2006
Posts: 1033
Own Kudos [?]: 251 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 14:42
To me :)

o p(2 bad apples) = 15*14 / (30*29) = 7/29
o p(2 bad oranges) = 6*5 / (30*29) = 1/29

Then,
o P(2 bad orange & 2 bad apples) = p(2 bad apples) * p(2 bad oranges) = 7/29 * 1/29 = 7/(29)^2
User avatar
IrinaOK
Senior Manager
Senior Manager
Joined: 22 Aug 2007
Posts: 276
Own Kudos [?]: 465 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 15:01
nitinneha wrote:
I found this problem on the internet while trying to find some practice material:

Tom has 30 apples, 15 of them are bad.Steve has 30 oranges and 6 of them are bad. Both Tom and Steve have to put two apples and two oranges in a basket at random. What is the probability that the basket would have exactly two bad apples and two bad oranges?

I tried to solve it but looks like something is missing..........can someone help.


agree with calculations 7/29 x 1/29 = 7/29^2, but the result seems too low...
User avatar
Fig
VP
VP
Joined: 01 May 2006
Posts: 1033
Own Kudos [?]: 251 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 15:16
IrinaOK wrote:
nitinneha wrote:
I found this problem on the internet while trying to find some practice material:

Tom has 30 apples, 15 of them are bad.Steve has 30 oranges and 6 of them are bad. Both Tom and Steve have to put two apples and two oranges in a basket at random. What is the probability that the basket would have exactly two bad apples and two bad oranges?

I tried to solve it but looks like something is missing..........can someone help.


agree with calculations 7/29 x 1/29 = 7/29^2, but the result seems too low...


Well... it's 1 chance on 120 to have this specific set :)... I think it's fine, the number of bad orange is low too :)

If the number of bad oranges were also equal to the good one, a set like this would have 1 chance on 17 to be...
User avatar
KillerSquirrel
Director
Director
Joined: 08 Jun 2005
Posts: 523
Own Kudos [?]: 559 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 15:21
Fig wrote:
To me :)

o p(2 bad apples) = 15*14 / (30*29) = 7/29
o p(2 bad oranges) = 6*5 / (30*29) = 1/29

Then,
o P(2 bad orange & 2 bad apples) = p(2 bad apples) * p(2 bad oranges) = 7/29 * 1/29 = 7/(29)^2


Yes - perfect as always - the answer should be 7/(29^2)

:)
User avatar
Fig
VP
VP
Joined: 01 May 2006
Posts: 1033
Own Kudos [?]: 251 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 15:27
KillerSquirrel wrote:
Fig wrote:
To me :)

o p(2 bad apples) = 15*14 / (30*29) = 7/29
o p(2 bad oranges) = 6*5 / (30*29) = 1/29

Then,
o P(2 bad orange & 2 bad apples) = p(2 bad apples) * p(2 bad oranges) = 7/29 * 1/29 = 7/(29)^2


Yes - perfect as always - the answer should be 7/(29^2)

:)


Thanks :)... U are not that bad too ;).... Did u fix a date for your test? :)

[I know... I asked u it one time already... Perhaps, this time I will have answer :wink: :wink: ... Never giving up ! :wink: ]
User avatar
KillerSquirrel
Director
Director
Joined: 08 Jun 2005
Posts: 523
Own Kudos [?]: 559 [0]
Given Kudos: 0
Send PM
Re: I found this problem on the internet while trying to find [#permalink] New post   26 Oct 2007, 15:29
Fig wrote:
KillerSquirrel wrote:
Fig wrote:
To me :)

o p(2 bad apples) = 15*14 / (30*29) = 7/29
o p(2 bad oranges) = 6*5 / (30*29) = 1/29

Then,
o P(2 bad orange & 2 bad apples) = p(2 bad apples) * p(2 bad oranges) = 7/29 * 1/29 = 7/(29)^2


Yes - perfect as always - the answer should be 7/(29^2)

:)


Thanks :)... U are not that bad too ;).... Did u fix a date for your test? :)

[I know... I asked u it one time already... Perhaps, this time I will have answer :wink: :wink: ... Never giving up ! :wink: ]


My test will be ~ December

:)
GMAT Club Bot
gmatclubot
Re: I found this problem on the internet while trying to find [#permalink]
26 Oct 2007, 15:29
 1   2   
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