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

It is currently 22 Oct 2014, 04:48

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

m17, q36

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 10 Jul 2009
Posts: 131
Location: Ukraine, Kyiv
Followers: 2

Kudos [?]: 38 [0], given: 60

m17, q36 [#permalink] New post 22 Nov 2009, 03:04
The probability that event A will occur is 20%. If event A occurs, the probability that event B will occur is 30%. What is the probability that event A will occur but event B will not?

1/10
7/55
5/36
7/50
5/24

I agree with OE here, but I do not agree with the solving method.
OE states:
The probability that event A will occur but event B will not = (the probability that event A will occur)*(1 - the probability that event B will occur) =
BUT: the solution is: 1/5*(1-0.3)=1/5*7/10=7/50.

May be I misinterpreted the question stem, but for me the probability that event B WILL occur is 1/5*0.3. Isn't it?
Please, help.
_________________

Never, never, never give up

Senior Manager
Senior Manager
avatar
Joined: 31 Aug 2009
Posts: 422
Location: Sydney, Australia
Followers: 6

Kudos [?]: 115 [0], given: 20

Re: m17, q36 [#permalink] New post 22 Nov 2009, 04:07
I think the OE is correct. The question asks what is the probability that B will NOT occur.

We want P(A) and P(Not B). This translates to:
P(A) * P(Not B) = P(A) * (1-P(B))
P(A) = 20%
P(B) = 30%
1-P(B) = 1-30% = 70%

P(A) * (1-P(B)) = 20%*70% = 1/5 * 7/10 = 7/50
Intern
Intern
avatar
Joined: 13 Sep 2011
Posts: 2
Location: Singapore
Concentration: Finance, Economics
GMAT 1: 720 Q50 V37
GRE 1: 1430 Q790 V640
GPA: 3.1
Followers: 0

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

Re: m17, q36 [#permalink] New post 29 Oct 2011, 17:41
I disagree with the explanation.

I agree that the final solution is P(A) * [1-P(B)].
& P(A) = 0.2

However regarding P(B) the question says;
" If event A occurs, the probability that event B will occur is 30%"
therefore P(B/A) = 0.3 and not P(B) = 0.3

In the explanation P(B) has been assumed to be 0.3, this does not look right to me.

I think P(B/A) = P (A and B) / P(A) = 0.3 = [P(A) + P(B) - P(A or B)] / P(A)
Director
Director
avatar
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 549
Location: India
GMAT 1: 640 Q43 V34
GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)
Followers: 2

Kudos [?]: 32 [0], given: 562

Re: m17, q36 [#permalink] New post 24 Feb 2013, 02:49
bunuel,

Why on earth is ' If event A occurs' is included in the question. This doesn't seem alright.

Regards,
SAch
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1197992

Re: m17, q36   [#permalink] 24 Feb 2013, 02:49
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic M17 study 11 02 Oct 2009, 23:31
Experts publish their posts in the topic m 17 #27 pmal04 9 27 Jun 2009, 12:05
18 Experts publish their posts in the topic m17 #8 sharmar 19 05 Dec 2008, 18:08
8 Experts publish their posts in the topic M17Q5 ventivish 20 30 Oct 2008, 17:05
1 Experts publish their posts in the topic M17-16 sondenso 17 26 May 2008, 02:55
Display posts from previous: Sort by

m17, q36

  Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: WoundedTiger, Bunuel



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®.