GNP

[deepesh.gupta]

To avoid economic collapse, Russia must increase its GNP by 20%. However, due to the structure of its economy, if the 20% threshold is reached, then a 40% increase in GNP is achievable.

Assuming that the above statements are true, which one of the following must also be true?
(A) If ethnic strife continues in Russia, then a 20% increase in GNP will be unattainable.
(B) If a 40% increase in Russia's GNP is impossible, its economy will collapse.
(C) If Russia's GNP increases by 40%, its economy will not collapse.
(D) If the 20% threshold is reached, then a 40% increase in GNP is achievable and a 60% increase is probable.
(E) If Russia's economy collapses, then it will not have increased its GNP by 40%.

[pradeepkaushal9518]

imo D is the answer

A. out of passage
B. no even if 20 % is achieved it economy will not collapse.
C. No if it is less than 20 % then it will collapse.
D. correct. 20 % is threshold value after which 40 % is achieve bale
E.Irrelevent

[tpr-becky]

I disagree becuase answer choice D includes "and a 60 percent increase is probable" no where in the sentence does it talk about a 60%

the right asnwer is B because if russia doesn't reach 20% it WILL collapse and if it reaches 20% then 40% is possible. therefore if 40% is impossible then they must not have reached the 20% which means the economy will collapse.

[pradeepkaushal9518]

But madam if the economy reached 20 % then it may or may not reach 40 %, as reaching 40 % is achievable but it is not sure that it will reach. B states that if 40 % is impossible then the economy will collapse.

ya in D 60 % is additional data

what is the OA

[Phirozz]

I disagree becuase answer choice D includes "and a 60 percent increase is probable" no where in the sentence does it talk about a 60%

the right asnwer is B because if russia doesn't reach 20% it WILL collapse and if it reaches 20% then 40% is possible. therefore if 40% is impossible then they must not have reached the 20% which means the economy will collapse.

I am agree with B.
if A implies B, then negation B implies negation A. This is what option B says..

C is a close contender but its wrong because we cannot conclude B implies A.

[paes]

I disagree becuase answer choice D includes "and a 60 percent increase is probable" no where in the sentence does it talk about a 60%

the right asnwer is B because if russia doesn't reach 20% it WILL collapse and if it reaches 20% then 40% is possible. therefore if 40% is impossible then they must not have reached the 20% which means the economy will collapse.

C looks a better choice.
The first statement says that "To avoid a collapse, 20% increase is MUST". So obviously a 40% increase will save Russia from economic collapse.

B also looks right from following :
A -> B then !B -> !A

[tpr-becky]

This is a classic necessary/sufficient argument. a 20% increase is necessary to be sure that it doesn't collapse, but on its' own it isn't sufficient to protect against other causes.

a 40% increase will not save it from collapse as the increase is only one factor of the collapse. we know it will collapse if it doesn't get 20% but that doesn't mean it could collapse for another reason even if it gets the 20%. Even if it gets 40% it could still collapse from an entirely separate problem so E is not necessarily true.

[paes]

This is a classic necessary/sufficient argument. a 20% increase is necessary to be sure that it doesn't collapse, but on its' own it isn't sufficient to protect against other causes.

a 40% increase will not save it from collapse as the increase is only one factor of the collapse. we know it will collapse if it doesn't get 20% but that doesn't mean it could collapse for another reason even if it gets the 20%. Even if it gets 40% it could still collapse from an entirely separate problem so E is not necessarily true.

Thanks:
It is clear now.

[deepesh.gupta]

OA is B

Thanks becky for the explaination.

This is a classic necessary/sufficient argument. a 20% increase is necessary to be sure that it doesn't collapse, but on its' own it isn't sufficient to protect against other causes.

a 40% increase will not save it from collapse as the increase is only one factor of the collapse. we know it will collapse if it doesn't get 20% but that doesn't mean it could collapse for another reason even if it gets the 20%. Even if it gets 40% it could still collapse from an entirely separate problem so E is not necessarily true.

[gmatmachoman]

This is a classic necessary/sufficient argument. a 20% increase is necessary to be sure that it doesn't collapse, but on its' own it isn't sufficient to protect against other causes.

a 40% increase will not save it from collapse as the increase is only one factor of the collapse. we know it will collapse if it doesn't get 20% but that doesn't mean it could collapse for another reason even if it gets the 20%. Even if it gets 40% it could still collapse from an entirely separate problem so E is not necessarily true.

Becky,
I am taking my test in the near future. To reinforce my fundae on Necessary/sufficient conditional reasoning, Please explain them more:

I understand that sufficient conditions forms the universal set of condition & necessary condition forms the sub-set of them.

Am i correct??

Say , For a event Z to occur,{ A, B, C, D, E} items has to happen. This forms the sufficient set conditions

Among that {E,F, G} is also necessary for the event Z to occur. This forms necessary set of conditions.

But it's NOT necessary that {E,F,G} alone will lead to event Z.

Please throw some common example which shall come handy for us to recollect during the test.

[frank1]

This is a classic necessary/sufficient argument. a 20% increase is necessary to be sure that it doesn't collapse, but on its' own it isn't sufficient to protect against other causes.

a 40% increase will not save it from collapse as the increase is only one factor of the collapse. we know it will collapse if it doesn't get 20% but that doesn't mean it could collapse for another reason even if it gets the 20%. Even if it gets 40% it could still collapse from an entirely separate problem so E is not necessarily true.

To be frank i was also thinking E....as i felt it would imply same thing as B(Indirectly)...

My logic was,backward solving
he didnt reached y ie 40 (no other way)
if he had reached x (20) he will automatically reach y (40) (no exception as not mentioned)
if he didnt reach x(20) he is absent (collapse)

he didnt reach y that means he was not in x ...so he was absent (collapse)

I have read in numerous book that teach "dont inject any extra information,your experience,guessing other than stated or given in the question" or dont fill the blanks yourself .
So is it right guessing that there can other factors as well in this question...(it will be using extra info other than question)
am i wrong in thinking that?

I personally feel if we fill gaps like this, every CR question would take completly different turn.

Just a query with respect.

[tpr-becky]

You certainly should not fill gaps with outside information but what I am talking about is the logic of the argument, not outside information. you can always consider that something else could happed unless is is specifically stated that it won't. for instance if the argument says it WILL rain tomorrow then you can't imagine that it won't but if the argument says it won't rain unless it is 40 degrees outside then you have to understand that things can happen that will make it not rain and that even if it is 40 degrees outside that rain is not guaranteed but if it is not 40 degrees outside it cannot rain.

[frank1]

well mam,
i think i got what you have said,but to be frank i am still not convinced....

You certainly should not fill gaps with outside information ......
......unless is is specifically stated that it won't. ...............
you have to understand that things can happen that will make it not rain and that even if it is 40 degree.

Yup,so as said in those lines we cannot conclude/guess any thing unless it is specifically stated....(in question)
so unless nothing has been specifically stated about "things can happen that will make it not rain" there is no reason to guess a extra variable here i guess...
It has not provided that information,that means there are no such things(atleast for the sake of question here)
If there were any,the question should mention it
besides, it is not inference question as well...

any way,no offence but i think, it is what/how the author of question thought while writing the question,so it holds and that is what matters for now.... so may be i will have to go with B but i am still not convinced......lol(until my logic is not satisfied....)

[Testluv]

received a pm:

To reinforce my fundae on Necessary/sufficient conditional reasoning, Please explain them more:

This:

I understand that sufficient conditions forms the universal set of condition & necessary condition forms the sub-set of them.

is certainly correct.

In a sentence that yields a formal logic relatonship, because it is a relationship, there will be at least 2 ideas. If you know you are in a formal logic sentence, you can ask:

"what are the two ideas?"

and one of these 2 questions:

1) "which idea is sufficient for (ie, guarantees or entails) the other?"

or

2) "which idea is necessary (ie, needed for) the other?"

We ask question 1 if there is "sufficiency" language in the sentence while we ask question 2 if we have "necessary" language.

For example: To be in Pune, you must be in India.

--what are the 2 ideas?...Pune and India

"Must" is necessary language....so which idea is necessary (for the other)?...India. Being in India is necessary for being in Pune while being in Pune is sufficient to conclude that you are in India.

We could write this algebraically:


Pune --> India

We would read this as "if you are in Pune, then you are in India." The condition on the left is always sufficient but unnecessary for the condition on the right (you don't have to be in Pune in order to be in India). Conversely, the condition on the right is necessary but insufficient for the one on the left (being in India doesn't guarantee that you are in Pune):

suff....................Nec
Pune------------>India
(not nec)...........(not suff)

On the GMAT, of course, you don't need to know how to translate sentences into written conditional statements. But it is good to understand the concept, recognize the rare instances where it is tested, and understand the distinction between sufficiency and necessity. You want to be able to think about it verbally. Again, when it does show up on the GMAT, it will almost for sure be about understanding the conceptual distinction between suff/nec.

[Testluv]

To avoid economic collapse, Russia must increase its GNP by 20%. However, due to the structure of its economy, if the 20% threshold is reached, then a 40% increase in GNP is achievable.

Assuming that the above statements are true, which one of the following must also be true?
(A) If ethnic strife continues in Russia, then a 20% increase in GNP will be unattainable.
(B) If a 40% increase in Russia's GNP is impossible, its economy will collapse.
(C) If Russia's GNP increases by 40%, its economy will not collapse.
(D) If the 20% threshold is reached, then a 40% increase in GNP is achievable and a 60% increase is probable.
(E) If Russia's economy collapses, then it will not have increased its GNP by 40%.

This is certainly an LSAT (or LSAT-like) question. You could get something like this on the GMAT, but the chances are quite slim. The first sentence yields the following conditonal statement:

If Russia avoids economic collapse, then it increases GNP by 20%.
(avoid ec. coll.----> increase GNP 20%)

The second sentence yields:

if it increases GNP by 20%, then 40% is possibe.
(increase GNP 20%----> 40% possible)

Note that the right hand side of the first conditional statement is also the left-hand side of the second. Thus:

if Russia avoids economic collapse, then 40% is possible,

whose contrapositive is:

if 40% is NOT possible (ie, IS impossible), then Russia will NOT avoid economic collapse (ie, WILL collapse).

Which, of course, is a perfect match to choice B.

(Choices A and D are outside the scope while chioces C and E involve mixing up sufficient and necessary conditions, which is the same thing as making a mistake in contraposing).

Now, we could also had just reasoned it through verbally as Becky did. For any fomal logic that appers on the GMAT, if you are a good reasoner, then that will be sufficient; no need to write down if-then statements (although you certainly can if you find it helps). Again, this must be an LSAT question; wrong answers on the GMAT would never test your technical contraposing skills this vigorously.

_______________________


When it comes to formal logic on the LSAT, there are exactly four sub-skills we have to have nailed down:

-identifying (in the first place, we need to identify that a sentence can yield a formal logic relationship)

-translating (we can translate the Englsh sentence into an algebraic one)

-contraposing (for every conitional statement, there is always exactly one other way of stating it; a contrary way of expressing the same positive information--the contrapositive)

-connecting (if the right hand side of one conditional statement is the left hand side of another, we can connect the two)

Note that I applied all four of these skills to prove that choice B must be true.