Necessary and sufficeint Questions : GMAT Critical Reasoning (CR)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 19 Jan 2017, 19:49

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Necessary and sufficeint Questions

Author Message
TAGS:

### Hide Tags

VP
Status: Final Lap Up!!!
Affiliations: NYK Line
Joined: 21 Sep 2012
Posts: 1096
Location: India
GMAT 1: 410 Q35 V11
GMAT 2: 530 Q44 V20
GMAT 3: 630 Q45 V31
GPA: 3.84
WE: Engineering (Transportation)
Followers: 37

Kudos [?]: 527 [0], given: 70

### Show Tags

29 Dec 2012, 16:29
2
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 2 sessions

### HideShow timer Statistics

Hello all

I am initiating this discussion to clear my doubt on Necessary and Sufficient questions.

Sufficient condition : This is the part of conditional statement that indicates the occurance of necessary condition.
Necessary Condition : This condition is a part of the condition statement the occurance of it is required for the sufficient condition.
Typical example:-

If you get an A+, then you must have studied

Sufficient Condition : Get an A+
Necessary condition: You must have studied.

Another example
People who drive fast are dangerous

Sufficient condition: Drive fast
Necessary condition: Dangerous

My doubt is should we consider parallel thinking in such question i.e. Should we think that A dangerous person can have several traits and driving fast is one of them.
Or When we are considering Necessary and Sufficient condition we must stick to the fact that there exists only one condition as stated in the statement.
Is it correct to say " People who are dangerous, its not necessary that they drive fast"
Justification: There may be many people who are veteran criminal but while driving drive slowly because they do not want accident.

My Query is Should we restrict ourselves to the two conditions itself when answering such question or think logically as we do on all other CR questions. If we follow the logical procedure then the the mentioned statement with justification should be correct. But if we just restrict ourselves to two events than we can write it as " People who are not dangerous, they do not drive fast" i.e People whoare dangerous must drive fast...Its illogical in real world.

PLs help me to clear my doubts.
If you have any questions
New!
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7125
Location: Pune, India
Followers: 2136

Kudos [?]: 13655 [1] , given: 222

Re: Necessary and sufficeint Questions [#permalink]

### Show Tags

29 Dec 2012, 18:40
1
KUDOS
Expert's post
Archit143 wrote:
Hello all

I am initiating this discussion to clear my doubt on Necessary and Sufficient questions.

Sufficient condition : This is the part of conditional statement that indicates the occurance of necessary condition.
Necessary Condition : This condition is a part of the condition statement the occurance of it is required for the sufficient condition.
Typical example:-

If you get an A+, then you must have studied

Sufficient Condition : Get an A+
Necessary condition: You must have studied.

Another example
People who drive fast are dangerous

Sufficient condition: Drive fast
Necessary condition: Dangerous

My doubt is should we consider parallel thinking in such question i.e. Should we think that A dangerous person can have several traits and driving fast is one of them.
Or When we are considering Necessary and Sufficient condition we must stick to the fact that there exists only one condition as stated in the statement.
Is it correct to say " People who are dangerous, its not necessary that they drive fast"
Justification: There may be many people who are veteran criminal but while driving drive slowly because they do not want accident.

My Query is Should we restrict ourselves to the two conditions itself when answering such question or think logically as we do on all other CR questions. If we follow the logical procedure then the the mentioned statement with justification should be correct. But if we just restrict ourselves to two events than we can write it as " People who are not dangerous, they do not drive fast" i.e People whoare dangerous must drive fast...Its illogical in real world.

PLs help me to clear my doubts.

We discuss necessary and sufficient conditions in detail in our book. It is an extremely important concept. There is a diagram that looks like this:

Necessary 1 ----->
Necessary 2------>
Necessary 3------> Sufficient Condition
...

All necessary conditions together lead to the sufficient condition. If the sufficient condition takes place, it means all necessary conditions took place. If one necessary condition takes place, we dont know whether the sufficient condition took place or not since we dont know whether the other necessary conditions took place. If even one necessary condition did not take place we can easily say that the sufficient condition did not take place.

People who drive fast are dangerous

Sufficient condition: Drive fast
Necessary condition: Dangerous

This means you need to be dangerous to be able to drive fast. To 'drive fast', there are various necessary conditions. 'Being dangerous' is one of them.

Quote: "Should we think that A dangerous person can have several traits and driving fast is one of them."
No, you should think that people who drive fast have several traits. Being dangerous is one of them. The sufficient conditions could need many necessary conditions. Not the other way around.

Quote: "Is it correct to say " People who are dangerous, its not necessary that they drive fast"

Yes it is. Being dangerous is a necessary condition. We don't know whether it alone leads to the sufficient condition of driving fast.

Check out my recent posts on my blog (link is in my signature). They tackle necessary and sufficient conditions.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199 Veritas Prep Reviews VP Status: Final Lap Up!!! Affiliations: NYK Line Joined: 21 Sep 2012 Posts: 1096 Location: India GMAT 1: 410 Q35 V11 GMAT 2: 530 Q44 V20 GMAT 3: 630 Q45 V31 GPA: 3.84 WE: Engineering (Transportation) Followers: 37 Kudos [?]: 527 [0], given: 70 Re: Necessary and sufficeint Questions [#permalink] ### Show Tags 29 Dec 2012, 18:49 HI Karishma That means If just necessary condition is mentioned for an action to be sufficient we should not assume that there are many others, If it is not explicitly mentioned in the argument. Necessary1--> Sufficient There may be many other but we ar oncerned her only about necessary 1 Necessary1, Necessary2, Necessary3------------> Sufficient All 3 are needed for the condition to be sufficient.Other than these we are not concerned about any.... regards Archit Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 7125 Location: Pune, India Followers: 2136 Kudos [?]: 13655 [0], given: 222 Re: Necessary and sufficeint Questions [#permalink] ### Show Tags 29 Dec 2012, 19:01 Archit143 wrote: HI Karishma That means If just necessary condition is mentioned for an action to be sufficient we should not assume that there are many others, If it is not explicitly mentioned in the argument. Necessary1--> Sufficient There may be many other but we ar oncerned her only about necessary 1 Necessary1, Necessary2, Necessary3------------> Sufficient All 3 are needed for the condition to be sufficient.Other than these we are not concerned about any.... regards Archit If a necessary condition is mentioned for a sufficient condition, we know that there is at least this condition necessary. There could be others too, we should not forget that. This necessary condition alone may not be enough to make the sufficient condition take place. Remember: Necessary1, Necessary2, Necessary3------------> Sufficient All 3 are required to make the sufficient happen. But if the sufficient happens, we know all three necessary conditions took place. _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

Veritas Prep Reviews

Intern
Joined: 16 Oct 2015
Posts: 8
Followers: 0

Kudos [?]: 0 [0], given: 1

Re: Necessary and sufficeint Questions [#permalink]

### Show Tags

08 May 2016, 01:54
HI,
How to differentiate between sufficient and necessary questions ? Are there any keywords that differentiate the two ?
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7125
Location: Pune, India
Followers: 2136

Kudos [?]: 13655 [0], given: 222

Re: Necessary and sufficeint Questions [#permalink]

### Show Tags

08 May 2016, 21:45
SecondTymRockStar wrote:
HI,
How to differentiate between sufficient and necessary questions ? Are there any keywords that differentiate the two ?

http://www.veritasprep.com/blog/2012/11 ... tatements/
http://www.veritasprep.com/blog/2012/12 ... tatements/
http://www.veritasprep.com/blog/2012/12 ... onditions/
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for \$199

Veritas Prep Reviews

Re: Necessary and sufficeint Questions   [#permalink] 08 May 2016, 21:45
Similar topics Replies Last post
Similar
Topics:
21 The removal of hillsides and mountaintops, necessary for 14 20 Aug 2011, 23:08
2 The removal of hillsides and mountaintops, necessary for 15 16 May 2011, 19:16
1 Jordan: If a business invests the money necessary to 5 09 Dec 2010, 12:40
The school board has determined that it is necessary to 3 08 Apr 2010, 09:30
Even in a democracy, it is necessary to restrict the 6 03 Jun 2008, 04:43
Display posts from previous: Sort by