NEW HERE? LEARN MORE
closeclose
Last visit was: 25 Apr 2024, 04:09 It is currently 25 Apr 2024, 04:09
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

1) Two anti-aircraft guns are firing at 4 planes. P (they

User avatar
Konstantin Lynov
Manager
Manager
Joined: 24 Jun 2003
Posts: 71
Own Kudos [?]: 13 [0]
Given Kudos: 0
Location: Moscow
Send PM
1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   08 Aug 2003, 02:58
1) Two anti-aircraft guns are firing at 4 planes. P (they are firing at the same plane)?
2) Three anti-aircraft guns are firing at 4 planes. P (they are firing at the same plane)?



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!
avatar
stolyar
VP
VP
Joined: 03 Feb 2003
Posts: 1012
Own Kudos [?]: 1629 [0]
Given Kudos: 0
Send PM
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   08 Aug 2003, 03:43
(1) 1*1/4=1/4

(2) 1*1/4*1/4=1/16
User avatar
Konstantin Lynov
Manager
Manager
Joined: 24 Jun 2003
Posts: 71
Own Kudos [?]: 13 [0]
Given Kudos: 0
Location: Moscow
Send PM
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   08 Aug 2003, 11:47
May I... explain? pls see previous message
avatar
stolyar
VP
VP
Joined: 03 Feb 2003
Posts: 1012
Own Kudos [?]: 1629 [0]
Given Kudos: 0
Send PM
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   08 Aug 2003, 12:04
sure you may
your explanations are welcome
User avatar
MBA04
Manager
Manager
Joined: 03 Jun 2003
Posts: 51
Own Kudos [?]: 4 [0]
Given Kudos: 0
Location: Uruguay
Send PM
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   12 Aug 2003, 06:39
1) 1/4 * 1/4 *4 = 1/4
2) 1/4*1/4*1/4*4 = 1/16

Each anti air craft has 1/4 prob to be shooting at one plane, so 1/4*1/4 (two anti air craft). Then we multiply by 4 because we have 4 planes to choose
User avatar
p_malh
Intern
Intern
Joined: 20 Aug 2003
Posts: 34
Own Kudos [?]: 1 [0]
Given Kudos: 0
Location: USA
Send PM
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   25 Aug 2003, 03:55
Quote:
1) 1/4 * 1/4 *4 = 1/4
2) 1/4*1/4*1/4*4 = 1/16

Each anti air craft has 1/4 prob to be shooting at one plane, so 1/4*1/4 (two anti air craft). Then we multiply by 4 because we have 4 planes to choose



Mbao4,

Shouldn't the first one be multiplied by 6 instead of 4, since we have 4C2 ways to choose 2 planes out of 4?

Please explain
User avatar
Konstantin Lynov
Manager
Manager
Joined: 24 Jun 2003
Posts: 71
Own Kudos [?]: 13 [0]
Given Kudos: 0
Location: Moscow
Send PM
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink] New post   27 Aug 2003, 12:12
p_malh wrote:
Quote:
1) 1/4 * 1/4 *4 = 1/4
2) 1/4*1/4*1/4*4 = 1/16

Each anti air craft has 1/4 prob to be shooting at one plane, so 1/4*1/4 (two anti air craft). Then we multiply by 4 because we have 4 planes to choose



Mbao4,

Shouldn't the first one be multiplied by 6 instead of 4, since we have 4C2 ways to choose 2 planes out of 4?

Please explain


Before Mba answers, let me try.

Think about two planes separately: the probability that one is firing is 100% or 1 (appears from the question stem). Now, the P that the second gun is firing at the same plane as the first one is 1/4, is't it? - four planes - one gun - this should be clear.

Multiply to get the total P. 1*1/4=1/4
Gabish?



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 above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: 1) Two anti-aircraft guns are firing at 4 planes. P (they [#permalink]
27 Aug 2003, 12:12
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