Establish relationship in CR between two entities

Question

Question
For the economy to grow, spending must increase year on year. Last year there was no consumer spending.

spending increase year on year = A
economy to grow = B

1. Am I correct in stating that A leads to B (A --> B) ? i.e spending increase year on year --> economy grows

or in CR am I to write it as economy grows --> spending must have increased year on year

Basically how I write the above affect the way I negate, ie not B --> not A.

Please advise how the relationship should be established in CR?

DinoPen · Answer

Yes. You are correct
A -> B

What do you mean by negate?
Inverse: ~A -> ~B
Converse B -> A
Contrapositive: ~B -> ~A

All of these statements are equivalent.

cosmiquegmat11 · Answer

Thank you for your response.

How can converse be true?
A -> B does not mean B -> A

By negation I meant contrapositive. I understand A -> B , then Contrapositive: ~B -> ~A is true.

DinoPen · Answer

I mistyped my response. All four of these statements are not always true.

They are not all equivalent; HOWEVER, if the converse is true, then the inverse is true.
And, if the original statement is true (p->q) then the contrapositive is true.

And, there can be a situation where all statements are true.
Example: 
Statement If two angles are congruent, then they have the same measure.
Converse If two angles have the same measure, then they are congruent.
Inverse If two angles are not congruent, then they do not have the same measure.
Contrapositive If two angles do not have the same measure, then they are not congruent.

To figure out the 'truth', you would have to ask if it makessense. For instance, using your example, the economy can very well grow with a different factor. (it doesn't have to just be consumer spending -- but this gets into assumption questions etc)

EMPOWERgmatRichC · Answer

Hi cosmiquegmat11,

You're discussing 'causality' (the idea that A causes B to happen) and the idea of a 'contra-positive' (a logically equivalent statement to the causal one). While you will almost certainly see causality in at least one CR on Test Day, contra-positives are considerably rarer (and you might not deal with that idea at all on the Official GMAT). These ideas are far more frequently tested on the LSAT.

In simple terms, when you have A ---> B (re: "A" happened and that caused "B" to happen), the logical equivalent to that is "Not B" ---> "Not A" (re: since "B" did not happen, then "A" did not happen either).

Since this is a small issue in a small sub-set of Verbal questions, your time might be better spent honing skills that are worth more to your overall Score. Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:

Studies:
1) How long have you studied? How many hours do you typically study each week?
2) What study materials have you used so far?
3) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?

Goals:
4) What is your overall goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?

GMAT assassins aren't born, they're made,
Rich

Establish relationship in CR between two entities

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Establish relationship in CR between two entities

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards