Q21 - Most of the students who took Spanish 101 at the unive

[mshinners]

Question Type:
Inference.

Extra info: The inference is about students who took Spanish 101.

Stimulus Breakdown:
S101 Students -most-> Perfect attendance
C+ or lower → ~Perfect attendance

Answer Anticipation:
First, you'll notice that I rephrased "lower than a B-" as "C+ or lower". I'm expecting some trap answers about students with a B-.

Second, the statements have overlapping terms, but I'll need to take the contrapositive to combine them.

S101 Students -most-> PA
PA → B- or higher
____________________________
S101 Students -most-> B- or higher

Two things here. First, when I took the contrapositive, I again rewrote the term to be "B- or Higher". I'm going for clarity over concision here. Second, this argument is asking for an inference surrounding a quantified statement - the "most" statement. Learn the rules to combine them! We have flashcards to help.

A quick way to "math it out" and find that the inference here is a "most" (when most inferences from quantified statements are "some" statements) is to start with 100 S101 Students. Based on the statements, we know a minimum of 51 had perfect attendance, all of whom received a B- or higher. So at least 51/100 students received that grade, and thus most received that grade.

The correct answer will almost certainly be "Most S101 students received at least a B-."

Correct answer:
(E)

Answer choice analysis:
(A) Out of scope. It's not even certain that anyone received an A- or higher, since we only know about students who beat a B-.

(B) Illegal reversal of that second conditional.

(C) Tricky! This answer is why I was precise with my language. We can infer that most students received a B- or higher; this answer tries to mess that up by stating they beat a B-. It could be the case that almost everyone received exactly a B-.

(D) Illegal reversal/negation of the second statement.

(E) Bickety bam. Exactly what we predicted! If you learn the quantifier rules, you can knock this question out in under a minute.

Takeaway/Pattern:
Learn those quantifier inference rules! Download the flashcards from your Student Center. This question should be under a minute if you've sufficiently prepped for the topic.

#officialexplanation

[wowpersonage1]

I need help understanding why C is incorrect and E is the correct answer...

I diagrammed it out as:
S---most--->AEC
LBM---->~AEC

so based on the contrapositive

S----most---->AEC----->~LBM

(AEC=attend every class; LBM=lower than BMinus).

Doesn't that allow you to correctly infer that most students did not receive lower than a BMinus or phrased "Higher than a B Minus" which is answer choice C.

[johnlwolf91]

I struggled here as well. I eventually was able to figure out that in the world of answer C, half or more of the students in the class could have received a grade of B- or lower. This is because all grades lower than B- were students who missed at least one class, but notice that it says "a grade lower than B minus" which means that several or even all of the students who attended each class received a B- (they just cannot be below that grade). If so many students received exactly a B-, then we cannot say that most received higher than B-.

[jones.mchandler]

I struggled here as well. I eventually was able to figure out that in the world of answer C, half or more of the students in the class could have received a grade of B- or lower. This is because all grades lower than B- were students who missed at least one class, but notice that it says "a grade lower than B minus" which means that several or even all of the students who attended each class received a B- (they just cannot be below that grade). If so many students received exactly a B-, then we cannot say that most received higher than B-.

John got it. The stimulus states that students who received a grade lower than B- missed at least one class, which is to say, the highest grade these students received was a C+. The stim also states the most students attended every class session.

Like John said, (C) neglects the grade of an actual B-, because it states that most received a grade "higher than B-".

(E) is correct because it includes that grade of B- when it states that more than half received a grade "of B- or higher".

[selimazing]

There is an easier way to think about this question in pure mathematical terms (yay for math on LSAT!).

1. Most Students taking Spanish101 attended every class session.

Lets plug in some numbers here, lets say there are 10 students in total and most of them attended every class session. Whats Most? More than half. In this case, this would be 6 students out of 10 that attended every class session.

2. Each students who received a grade lower than B- missed at least one session

Since we know that more than half--those 6 people we talked about above attended every session, they can't possibly the ones getting B- or less because again they attended every class.

So what is left? the 4 students in the minority. Those 4 poor saps that missed at least one class session received a grade lower than B-.

So what can be infer from all this?

Since the 4 students will be the ones getting the B- and lower think about what that means for the 6 students that attended every class (or rather "most students")? Based on the facts above we can conclude that at least 6 students scored B- and or above. So "most" students scored B- and above.

That is what choice E says.

I hope this is of some help.

[gabcap1]

So what is left? the 4 students in the minority. Those 4 poor saps that missed at least one class session received a grade lower than B-.

I found your explanation helpful, selimazing! Thanks

One question I have about this part, though, is that it appears to assume that if you missed 1 class session you had to get a B- or lower. Is it not possible that you could miss a class session and still score above a B-?

[maryadkins]

Yes, if you missed one class or more, you can still score higher than a B minus. But if you got a B minus, you missed at least one class.

[jwms]

Yes, if you missed one class or more, you can still score higher than a B minus. But if you got a B minus, you missed at least one class.

Correct me if I'm wrong, but it's if you get a lower score than a B-, then you missed at least one class. If it was 'you get a B minus, then you missed one class', then (C) would be correct. That 'lower' modifier in the stimulus is the tricky part that separates trap AC (C) from TCR (E).

[ganbayou]

Hi,
I almost chose E but chose A in the end...
I was not sure about E because it says more than hald of the students received a grade of B-or higher, but there might be other factors influenced their grades, such as test score etc. Even though students attend all classes, they might have done poorly and it might result in receiving grade lower than B- isn't it?
In that case, I thought we cannot say "more than half"...maybe many Ss did poorly on exams for example and they received lower grades even though they attended all classes.
Could anyone explain this?

[maryadkins]

This question is really about formal logic. Most of the students were at every class. If you were at every class, you did not get lower than a B minus. (See discussion above for why.) That's (E). That means most of the students received a B minus or above.

Correct me if I'm wrong, but it's if you get a lower score than a B-, then you missed at least one class. If it was 'you get a B minus, then you missed one class', then (C) would be correct. That 'lower' modifier in the stimulus is the tricky part that separates trap AC (C) from TCR (E).

Yes! Thank you!

[AyakiK696]

I tried to answer this question by using the whole "Most S are PA" and "All PA are LB" but I guess it didn't work out since I couldn't get the sufficient conditions to match up. So should we only use that form if the sufficient conditions match up, and use the other form when the sufficient condition of the first statement and the necessary condition of the second statement chain up (writing "most" above the arrow)?

S = student
PA = perfect attendance
LB = Lower than B-

[ohthatpatrick]

It seems like that form works fine to me.

You're referring to:
Most A's are B
+...............All B's are C.
--------------------------------
Thus, Most A's are C.

Most S101 students had perf attendance.
+.................................ALL perf attendance had B- or higher.
-----------------------------
Thus, Most S101 students had a B minus or higher

That's what our correct answer (E) says.

[DavidH327]

I have a question about answer choice A:
At least some of the students who received A minus or higher attended every class
Why is it the case that A minus or higher does not qualify B- or higher?

Borrowing from your quote:
Most S101 students had perf attendance (attended every class) --> B- or higher.

Can't we say B-or higher SOME had attended every class? OR
Does it have to be B- AND higher SOME had attended every class??

Thank you in advance!

It seems like that form works fine to me.

You're referring to:
Most A's are B
+...............All B's are C.
--------------------------------
Thus, Most A's are C.

Most S101 students had perf attendance.
+.................................ALL perf attendance had B- or higher.
-----------------------------
Thus, Most S101 students had a B minus or higher

That's what our correct answer (E) says.

[ohthatpatrick]

I think you're just getting confused between Sufficient Assumption and Inference.

You're speaking as though we're looking for an answer that, IF TRUE, would allow us to establish something else.

You're saying, "If they have an A- or higher, then don't they have a B- or higher?"
Yes, but that's not our task.

We're being asked, "Given what we know, which answer also must be true".

We know that they have a B- or higher.

"Given that they have a B- or higher, do they HAVE to have an A- or higher?"

No, they could all have B-, B, or B+.

Hope this helps

[DavidH327]

Thank you for your response!
I guess my confusion came from trying to equate B- or higher as A- or higher.
But as you mentioned maybe all the students who attended every class had B-, B, or B+ and none had A- or higher.

And for the second part of my question:
everybody attended every class --> B - or higher
Can we infer that Some of students who had B - or higher attended every class?

I think you're just getting confused between Sufficient Assumption and Inference.

You're speaking as though we're looking for an answer that, IF TRUE, would allow us to establish something else.

You're saying, "If they have an A- or higher, then don't they have a B- or higher?"
Yes, but that's not our task.

We're being asked, "Given what we know, which answer also must be true".

We know that they have a B- or higher.

"Given that they have a B- or higher, do they HAVE to have an A- or higher?"

No, they could all have B-, B, or B+.

Hope this helps