Q21 - Any student who is not

[ManhattanPrepLSAT1]

Thanks for bring your question to the forum!

In some ways this question is fairly straight forward if you're familiar with conditional relationships and your task on sufficient assumptions. But the test-writer does a good job in hiding the simplicity of the argument behind convoluted language.

Here's the argument core expressed in notation:

~WHR ---> ~CRA
---------------------
~WHR ---> ~HG

(Notation Key: WHR = written homework required; CRA = complete reading assignments; HG = high grade)

The gap in the reasoning is:

~CRA ---> ~HG

And that is perfectly expressed in answer choice (A), which says that if you don't complete your reading assignments you will not get a high grade.

Our task on a sufficient assumption is to add a claim that will prove the conclusion. The conclusion in the stimulus is about not getting a high grade. That is never discussed in the evidence and so needs to be part of the correct answer.

(A) bridges the gap perfectly as stated above.
(B) is the negation of the gap in the reasoning. Expressed in notation it says CRA ---> HG
(C) is too narrow. It will not establish the conclusion that is about both highly motivated and non-highly motivated students.
(D) is too narrow. This answer choice doesn't mention students who are not highly motivated.
(E) is too weak. We need a strong answer as the conclusion is strong. "Some are not" (in the answer choice) is not enough to prove "no" (as is stated in the conclusion).

Does that help clear this one up?


#officialexplanation

[teteca41]

Can one of you brilliant minds help me break apart and understand this question?

[deleted copyrighted material]

[velvet]

I got tripped up on expressing the argument conclusion as:

Reading Assignments + ~WHR ---> ~HG,

Why didn't you add the "given several reading assignments" as part of the sufficient condition in the conclusion?

Thanks in advance.

[clare.ess]

I also got tripped up on diagramming the conditional statements in this problem. I ended up with an additional conditional statement in the middle concerning highly motivated students

~WHR > ~CRA
~WHR > HMN (Highly motivated students neglect reading)
~WHR > ~HG

I think I would have made the proper connection if I didn't have that third conditional statement in the middle. How do you know which parts are relevant to the argument?

[timmydoeslsat]

When you think about the first premise and how it states that any student ~required to hand in written hw ---> ~C

This would include those highly motivated students anyway. That second sentence is just like advertising the fact that even those highly motivated kids even succumb to this fact.

So our gap really is:

~R HI Wr HW ---> ~C
_____________________
~R HI Wr HW ----> ~HG

The gap is [~C ---> ~HG]

[jamiejames]

That middle piece is just extra information that is meant to trip you up and make you want to choose C/D/E :p

[wrosario2003]

little trick to gain some time...

As most of us already knew, or at least have realized after studying this type of question, known as a "Sufficient Assumption Question", the majority are diagram-able and is time consuming to diagram, connect, locate the gap, then close the gap which is the prediction to your right answer and then move to discard each answer choices until find the one that match your prediction... This is why I consider that this type of question are like speed bump design for the test taker to invest/ deprive time and energy and then move on to the next question a little bit more tired and maybe with a broken time parameter plan.

So please receive this caveat in good faith. First, be warn that this only works under the following condition and if does not discard the four(4) incorrect choices, solely leaving the correct one. It will help you eliminate at least some choices and giving you some advantage on pin pointing the correct one.

Constraint: (It works if....)

you can diagram the argument of this type of question, sufficient.

It employs a new term

and if...

the new term is the conclusion of the argument.

-------------------------------------------------------------------------

Taking for example this question, 22.

without diagramming the entire argument, I reasoned that the new term/ conclusion was: "... no student in that course will receive a high grade for the course" the conclusion is the necessary part of the argument.

So with that being said you can infer that the correct answer choice must meet a couple prerequisite to be right, which are:

1. it must contain the new term (since it needs to be connected to the premise in the argument)

2. since the answer choices will also be in a diagram format, the necessary part, which according to the conclusion/ new term, is negated. Therefore, if the new term is located in the sufficient side of the answer choices, then it must not negated, according to the contra-positive rules. Any optiions that present the new term in the nec. side not negated or in the suff. negated it contain a invalid format and you can eliminate it.

---Furthermore, you can logically eliminate by just assessing the essence of answer choice B, C, and D since they violate the aforementioned condition, leaving E and A.

---However, answer choice E employs the usage of the word "some" which is another word for "at least one" which is very weak. Now, this answer choice would be a contender if the stimulus also employs such weak quantitative term to reach it conclusion but that is not the case in argument or even is hardly the case on most sufficient type question, therefore it can be removed.

---This leaves you with answer choice A, which is matched with all that has been discussed to this point, making it the correct answer.


WARNING!!! please use this shortcut as a last result alternative... This is not intended to skip, nor to replace, any of the basic and essential strategy to attack this type of question.

Hope that this serve as some use...

Respectfully,

[hnadgauda]

Thanks for bring your question to the forum!

In some ways this question is fairly straight forward if you're familiar with conditional relationships and your task on sufficient assumptions. But the test-writer does a good job in hiding the simplicity of the argument behind convoluted language.

Here's the argument core expressed in notation:

~WHR ---> ~CRA
---------------------
~WHR ---> ~HG

(Notation Key: WHR = written homework required; CRA = complete reading assignments; HG = high grade)

The gap in the reasoning is:

~CRA ---> ~HG

And that is perfectly expressed in answer choice (A), which says that if you don't complete your reading assignments you will not get a high grade.

Our task on a sufficient assumption is to add a claim that will prove the conclusion. The conclusion in the stimulus is about not getting a high grade. That is never discussed in the evidence and so needs to be part of the correct answer.

(A) bridges the gap perfectly as stated above.
(B) is the negation of the gap in the reasoning. Expressed in notation it says CRA ---> HG
(C) is too narrow. It will not establish the conclusion that is about both highly motivated and non-highly motivated students.
(D) is too narrow. This answer choice doesn't mention students who are not highly motivated.
(E) is too weak. We need a strong answer as the conclusion is strong. "Some are not" (in the answer choice) is not enough to prove "no" (as is stated in the conclusion).

Does that help clear this one up?

I do not understand how the gap in the reasoning is: ~CRA ---> ~HG

Based on
~WHR ---> ~CRA
---------------------
~WHR ---> ~HG

I thought this meant that

~WHR ---> ~CRA
---> ~HG

Can you please explain how you determined the gap in the reasoning?

[hnadgauda]

I understand where the gap came from now after reviewing this question. Can we eliminate E because it pertains to highly motivated students and the gap involves all students?

[lunazhuyu]

I understand where the gap came from now after reviewing this question. Can we eliminate E because it pertains to highly motivated students and the gap involves all students?

Yes I think we can eliminate E on the basis you mention. Also for the same reason we can eliminate C and D. Highly motivated students is a sub-category of the students, but not the subject of the conclusion.

[at9037]

How did you get ~CRA ---> ~HG??

According to the LR book, A--->B and A--->C is NOT B--->C.

Also, why is option B not a valid answer?

[ohthatpatrick]

The 1st sentence:
not req'd to hand in written --> won't complete all reading

contrapositive:
complete all reading --> req'd to hand in written

------------------

The correct answer (A):
don't complete all reading --> won't earn a high grade

contrapositive:
earn a high grade --> complete all reading

(No A's are B = All A's are ~B = A --> ~B)

------------------

We can chain together the first sentence and choice (A) to get:
not req'd to hand in written -> won't complete all reading -> won't earn a high grade

This means that we have derived the conclusion:
not req'd to hand in written -------------------------------------> won't earn a high grade

We have to infer the trigger. i.e., we have to think, "If they aren't GIVEN any written assignments, then it's fair to say that they aren't REQUIRED TO HAND IN any written assignments."

-------------------

(B) is an illegal negation of the conclusion.

If I'm trying to prove that "If ~A, then ~B",
it doesn't help me at all to know "If A, then B",
because those are two completely different ideas.

[ChelseaK712]

This is such a basic question but what is the conclusion in this argument? Is it the first sentence, last sentence or neither? This question is asking us to find the assumption that best proves the conclusion, correct? Thanks for the help.