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

It is currently 22 Sep 2014, 20:42

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

The probability of shooting a target increases after a

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
User avatar
Joined: 17 Dec 2012
Posts: 395
Location: India
Followers: 13

Kudos [?]: 182 [0], given: 10

The probability of shooting a target increases after a [#permalink] New post 18 Mar 2013, 06:03
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

41% (02:14) correct 59% (01:05) wrong based on 71 sessions
The probability of shooting a target increases after a certain skill is enhanced and is equal to the new probability of NOT shooting the target. Given this fact, which of the following must be false?

A. The new probability of shooting the target is greater than 0.5
B. The original probability of shooting the target is less than 0.5
C. The original probability of NOT shooting the target and the new probability of shooting the target are the same
D. The original probability of shooting the target and that of NOT shooting the target are the same.
E. The sum of the original and the new probabilities of shooting the target is ALWAYS equal to 1.
[Reveal] Spoiler: OA

_________________

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

Classroom Courses in Chennai
Online and Correspondence Courses

2 KUDOS received
Manager
Manager
User avatar
Joined: 24 Jan 2013
Posts: 81
Followers: 5

Kudos [?]: 64 [2] , given: 6

Re: The probability of shooting a target increases after a [#permalink] New post 20 Mar 2013, 02:12
2
This post received
KUDOS
Quote:
The probability of shooting a target increases after a certain skill is enhanced and is equal to the new probability of NOT shooting the target. Given this fact, which of the following must be false?


I think this is a 700 problem.

If I understood well the question, we have:

  • initial probability of shooting target: P(success\;initial)
  • initial probability of not shooting the target: P(not\;success\;initial)
  • new probability of shooting target: P(success\;final)
  • new probability of not shooting the target: P(not\;success\;final)

Conditions given by problem:

(1) P(success\;initial)=1-P(not\;success\;initial)

(2) P(success\;final)=1-P(not\;success\;final)

(3) P(success\;initial)<P(success\;final)

(4) P(success\;initial)=P(not\;success\;final)

Therefore:

P(success\;final)=1-P(success\;initial)

then

P(success\;initial)<1-P(success\;initial) ---> P(success\;initial)<0.5

Conclusions:

(5) P(success\;initial)<0.5

(6) P(success\;final)>0.5

(7) P(not\;success\;final)<0.5

(8) P(not\;success\;initial)>0.5

(9) P(success\;final)=1-P(not\;success\;final) ---> P(success\;final)=1-P(success\;initial) ---> P(success\;final)+P(success\;initial)=1

Analysis of different options:

A. The new probability of shooting the target is greater than 0.5: TRUE, look at (6)
B. The original probability of shooting the target is less than 0.5: TRUE, look at (5)
C. The original probability of NOT shooting the target and the new probability of shooting the target are the same: TRUE, look at (4)
D. The original probability of shooting the target and that of NOT shooting the target are the same: FALSE
E. The sum of the original and the new probabilities of shooting the target is ALWAYS equal to 1: : TRUE, look at (9)
_________________

Does this post deserve KUDOS?

Free Prep: Self-prepare GMAT for free and GMAT Math tips for free
Free Flashcards: Free GMAT Flashcards

More: "All I wish someone had told me about GMAT beforehand"
There are many things you want to know before doing the GMAT exam (how is exam day, what to expect, how to think, to do's...), and you have them in this blog, in a simple way

Manager
Manager
User avatar
Joined: 24 Jan 2013
Posts: 81
Followers: 5

Kudos [?]: 64 [0], given: 6

Re: The probability of shooting a target increases after a [#permalink] New post 20 Mar 2013, 07:45
In fact, the key formula here to solve the whole problem is:

P(A)=1-P(not\;A)

Then differentiate between the initial situation and the new (or final) situation:

Initial: P(A)=1-P(not\;A)

New: P(Z)=1-P(not\;Z)

And link the formulas with the conditions given by the problem.
_________________

Does this post deserve KUDOS?

Free Prep: Self-prepare GMAT for free and GMAT Math tips for free
Free Flashcards: Free GMAT Flashcards

More: "All I wish someone had told me about GMAT beforehand"
There are many things you want to know before doing the GMAT exam (how is exam day, what to expect, how to think, to do's...), and you have them in this blog, in a simple way

Senior Manager
Senior Manager
User avatar
Joined: 17 Dec 2012
Posts: 395
Location: India
Followers: 13

Kudos [?]: 182 [0], given: 10

Re: The probability of shooting a target increases after a [#permalink] New post 24 Mar 2013, 18:07
SravnaTestPrep wrote:
The probability of shooting a target increases after a certain skill is enhanced and is equal to the new probability of NOT shooting the target. Given this fact, which of the following must be false?

A. The new probability of shooting the target is greater than 0.5
B. The original probability of shooting the target is less than 0.5
C. The original probability of NOT shooting the target and the new probability of shooting the target are the same
D. The original probability of shooting the target and that of NOT shooting the target are the same.
E. The sum of the original and the new probabilities of shooting the target is ALWAYS equal to 1.



1. Let p(i), q(i), be the initial probability of shooting and missing the target respectively and let p(n) and q(n) be the new probability of shooting and missing the target respectively.

Given:

1. p(i) + q(i) =1
2. P(n) + q(n) =1
3. p(n) > p(i)
4. p(i) = q(n)

Deductions:

5. q(n) + q(i) =1 ( from (1) and (4) )
6. p(n) + p(i) =1 ( from (2) and (4) ) - ( Choice E always true)

7. From ( 3) and (6), p(i) < 0.5 and p(n) > 0.5 - ( Choice A and Choice B always true)

8. From (1) and (6), q(i) = p(n) - ( Choice C always true)

9. From (3) and (8), q(i) > p(i) - ( choice D always false)

Therefore the answer is Choice D.
_________________

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

Classroom Courses in Chennai
Online and Correspondence Courses

SVP
SVP
User avatar
Joined: 06 Sep 2013
Posts: 1666
Location: United States
Concentration: Finance
GMAT 1: 710 Q48 V39
WE: Corporate Finance (Investment Banking)
Followers: 13

Kudos [?]: 165 [0], given: 274

GMAT ToolKit User
Re: The probability of shooting a target increases after a [#permalink] New post 24 Mar 2014, 08:56
SravnaTestPrep wrote:
The probability of shooting a target increases after a certain skill is enhanced and is equal to the new probability of NOT shooting the target. Given this fact, which of the following must be false?

A. The new probability of shooting the target is greater than 0.5
B. The original probability of shooting the target is less than 0.5
C. The original probability of NOT shooting the target and the new probability of shooting the target are the same
D. The original probability of shooting the target and that of NOT shooting the target are the same.
E. The sum of the original and the new probabilities of shooting the target is ALWAYS equal to 1.


Sravna, what's the source of this question?

I find a little bit out of scope of GMAT

Thanks
Cheers
J
Re: The probability of shooting a target increases after a   [#permalink] 24 Mar 2014, 08:56
    Similar topics Author Replies Last post
Similar
Topics:
Study for GMAT to increase probability for interview letitbegood 1 29 Apr 2013, 11:50
26 Experts publish their posts in the topic If the probability that Stock A will increase in value Baten80 17 17 Jan 2012, 11:49
If the probability is 0.6 that stock A will increase in pmenon 6 17 Nov 2007, 09:27
The snipers shoot a certain target. Their probabilities of bmwhype2 7 04 Nov 2007, 00:24
In a shooting competition, probability of A hitting target remgeo 4 28 Oct 2005, 03:12
Display posts from previous: Sort by

The probability of shooting a target increases after a

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.