Q20 - Students from outside the province

[jas770]

why is the correct answer E and not C?

[aileenann]

Good question. It's always important to know why an answer is correct and what an answer is incorrect. Let's go through all of tem.

First, since this question is asking us to draw a conclusion, it's really important to pay attention to scope. We don't want to overstep the bounds of what we know - which is often much more limited than it would be if we knew the same thing in the "real world" where we have plenty of common sense and background knowledge we can bring into play.

Let's go through the wrong answers first.

(A) is way way way off. We can't draw a causal relationship where they only told us two things happened and don't give us any causal relation between the two. Anyone who picked this would be falling for the correlation-causation fallacy the LSAT uses oh so often.

(B) has exactly the same problem as (A), just in the other direction.

(C) is tricky. This is another way the LSAT makes an answer look really good even if it's wrong. If you go back to the argument you will see that all we know is about the *proportion* of students. Proportions can go up or down without the number of students changing. Whenever you see the word proportion or ration, make a mental note that this tells you nothing about the absolute number of students!

(D) is also out of scope. We only know about Markland College not about any other college.

(E) had better be the answer because everything else is definitely wrong! This is very tricky because it's a hypothetical. Basically this is making use of the fact that students who are from outside the region were paying much more tuition. Therefore this is saying that if the average tuition ("per capita") has stayed the same even though there are proportionally less students paying the out of region tuition, this must mean that the in region students are making up the difference, which must mean that their tuition has gone up.

(E) is definitely tricky, so I'd recommend working this out - maybe even putting some numbers into the scenario to make it more concrete. Another way to go on this one (especially, since at #20 it is going to be one of the hardest on the LR section, most likely) is to be sure to eliminate the other 4 answers for the reasons we saw. If so, you can take a leap and pick (E) even if you aren't sure because you know that the other 4 cannot be the answer.

I hope this helps! Definitely get back to me if anything is still unclear.

[tzyc]

Hello,

I'm still not sure about (C)...
The stimulus says:
proportion of students who are not Marklanders has dropped to around 40%

Does this proportion compare to the proportion 10 years ago within the same category (not Marklanders)?
So, not comparing X to Y, but X to X(10 years ago)?

I'm not sure whether I made my question clear...

[cvfh17]

I understand your post but what about the risen of the college standards? it plays something in the argument, because the answer is about per capita revenue and has nothing to do with college risen standards?
thanks

[maryadkins]

I understand your post but what about the risen of the college standards? it plays something in the argument, because the answer is about per capita revenue and has nothing to do with college risen standards?

The rising standards only matters in that it drove the decline of non-Marklanders. Non-Marklanders pay more, and there are fewer of them now (they were at least 66% of the student body before, and now they're 40%).

Does this proportion compare to the proportion 10 years ago within the same category (not Marklanders)?
So, not comparing X to Y, but X to X(10 years ago)?

I'm not sure I follow your question, but basically, we don't know about the number of students in either category. We just know the proportion of one relative to the other went down. So say 10 years ago there were 1,000 students. 750 of them were non-Marklanders, and 250 were Marklanders. (C) asks if we know that the number of Marklanders has gone up (from 250), but what if the total number of students has fallen to 100. That means that even if Marklanders now make up 60%, there are only 60 of them.

As Aileen said, watch out for percentages versus absolutes and if this remains tricky for you, review it until you know it well.

[lrt1337]

So I don't really understand why E is correct, especially since the stimulus says at LEAST 2/3rds, meaning it could range from 66% to 99% (leaving one percent for the Marklanders, theoretically). Hence if it dropped from 99% to around 40% then, since the Marklanders are paying double the tuition, but their percentage actually dropped to more than half of what it was, then the tuition did not necessarily have to increase after all! Am I just seriously overthinking this? I can get it by POE now, but I'd really like to know the absolute logic behind this, especially with the use of "at least" and "around" - how are you supposed to determine any mathematical calculations with such imprecise language?

[sarahejlee]

I'm new to the forum, so apologies for beating around the bush.
I initially came to this thread to make sure that my thinking process was right, but I now see I could make some contribution this time

By providing this example, I think I could prove simultaneously why answer choice (C) is NOT NECESSARILY TRUE and (E) MUST BE TRUE.

Let's say there were 100 students enrolled at Central Markland College (hereafter referred to as CMC) and the tuition for residents was $100. Since at least 2/3 of the student body comprised of non-residents who paid double the residents' tuition ($200), let's suppose, for the purpose of simplification, that 70% of the student body were non-residents.

In sum, 10 years ago, we had 30 resident students each of whom paid $100 and 70 non-resident students each of whom paid double that amount, i.e. $200.

To compute the average tuition (tuition revenue received by CMC per head) = ( $100 x 30 + $200 x 70 ) / 100 = $170 per capita or per student

After 10 years, IF CMC is still earning per capita revenue of $170 and that the proportion of nonresidents has decreased to 40%, it MUST BE TRUE that the amount of contribution by residents has increased.

Let me give you another hypothetical situation.

After 10 years, the number of student body has increased. Say, the number of residents and nonresidents have BOTH increased to a total of 200. Here, since nonresidents make up 40% of the student body, there are 80 of them and the rest are residents (160 students).
See how (C) doesn't have to be true here for nonresident students' proportion to decrease relative to that of the residents?

So if the college is still earning $170 from each student, let's denote the new tuition as NT and see if NT equals $100 (which was the tuition for residents a decade ago).

170 = { ( NT x # of residents ) + ( double NT x # of nonresidents) } / new total number of students

170 x 200 = ( NT x 120 ) + ( 2NT x 80 )
34000 = 280NT
New Tuition (NT) = $121.something
*sorry I'm writing this on ipad and I'm way too lazy to use a calculator

So the tuition has indeed increased! (by $21 in our hypothetical example)

Hope this helps

[onguyen228]

I think I might have a similar way to understand this question. All we know is that the proportion of non-Marklands have decreased, and know nothing about total numbers or numbers for each group. Three scenarios could be occurring:

1. 40% drop is due to the decrease of non-Markland students.
2. 40% drop is due to increase of Markland students.
3. 40% drop is due to increase of Markland students and a decrease in non-Markland students.

Each scenario is possible. Which is why (C) is wrong. It could be true but not in every scenario, thus it isn't a must be true answer.

What do all the scenarios have in common? The ratio of Markland students to non-Markland students increases. So the average revenue the school receive per student (total of revenue from tuition divided by total number of students) will decrease, because remember non-markland students pay more dough for tuition.

Think of averaging your grades. You have three grades of 100, 100, and 100 (average of 100). And receiving a 50 will dramatically decrease your average to 87.5. And the school is like "hell no, we don't want a decreased per capita revenue, we better increase the tuition." If it were up to me they should all pay the same amount of tuition. It'd make life a lot easier.

[HansolL655]

Hello there,

I now understand why choice C is an answer choice that COULD BE TRUE, rather than MUST BE TRUE.

But I'm finding a weakness in choice E that is preventing me from reaching a full conciliation with this problem.

What we know:

Proportion of students (let's say Non-M for not from Markland) has decreased from equal to or greater than 66% of the student population to approximately 40% of the student population.

Choice E asks the reader to consider that the college's per capita revenue, otherwise known as total revenue divided by the number of students in order to get an average revenue per student, is constant after this change.

This can come from multiple ways, because, the decrease in proportion of Non-M students can come from different ways:

Way 1: Solely a decrease in Non-M students. Self explanatory.
Way 2: Increase in M students. Since the total number of students = M students + Non-M students, the proportion of Non-M students can decrease to approximately 40%, simply by admitting more M students.
Way 3: Both ways 1 and 2.

And this is where we see the problem. In order for Choice E to be must be true, one has to assume that Way 1 is the only way that the proportion of Non-M students decreased.

But let's suppose that it was actually Way 2. I believe this to be equally valid as Ways 1 and 3. Well, if this is the case, then tuition fees do not HAVE to increase. In fact, the reverse must be true. Yes, the M students pay half of what Non-M students pay. So if Non-M students pay 2x, then M students pay x. And if the proportion of Non-M students decrease, because the number of M students increase, then actually tuition fees must have decreased over the past 10 years, not increased.

The problem DOES NOT limit the total number of students to be constant.

[HansolL655]

Just seeing if anyone wishes to respond.