In the United States, of the people who moved [CR]

[nehajadoo]

In the United States, of the people who moved from one state to another when they retired, the percentage who retired to Florida has decreased by three percentage points over the past ten years. Since many local businesses in Florida cater to retirees, this decline is likely to have a noticeably negative economic effect on these businesses.
Which of the following, if true, most seriously weakens the argument?
A. Florida attracts more people who move from one state to another when they retire than does any other state.
B. The number of people who move out of Florida to accept employment in other states has increased over the past ten years.
C. There are far more local businesses in Florida that cater to tourists than there are local businesses that cater to retirees.
D. The total number of people who retired and moved to another state for their retirement has increased significantly over the past ten years.
E. The number of people who left Florida when they retired to live in another state was greater last year than it was ten years ago.


Source: Gmat Prep
OA is D

why is A incorrect?

Thanks!

[nehajadoo]

please help
exam in 3 days :(


thanks!

[tim]

I suppose your GMAT has come and gone, but I’ll answer the question in case others are interested. Remember that we have office hours and private tutoring for the truly urgent questions; there are a lot of students using this free service, and when you post here, you have to accept the fact that it could take a while to get your answer..

To answer this one, plug in your answer of choice and see what its effect on the argument is. Assume that Florida attracts more people than any other state does. If the percentage has decreased, that still means there could be a decrease in business even if Florida is still the most popular state for retirees..

[aanchalsinha]

Hi Tim,

I have 2 questions - regarding this particular qs and regarding argument type percentages vs numbers.

Regarding the above question, I chose D.

Since the question was based on the 3% stat, I figured the correct answer may revolve around the actual number of people who retired. So this thinking got me down to choices C & D. I picked D for the following reasoning,

conclusion: decrease in influx % --> -ve impact on eco of Florida
choice D: increase in people leaving --> -ve impact on eco of Florida

i.e. conclusion: A --> B
choice D: C --> B

I rejected choice C because it didn't talk about Florida.

regarding argument type percentages vs numbers

Is it safe to say that if the premise of the argument is based on percentages vs numbers,

for weakening qs: ans choice talking about actual numbers may weaken the argument as a whole. In other words it weakens the premise used as basis.

for assumption qs: ans choice talking about actual numbers must only kill the conclusion. If the conclusion is talking behaviour as opposed to the actual numbers this would be an incorrect choice. It would be much easier to explain this with regards to a particular qs which has been discussed here previously: a-recent-report-determined-that-although-only-three-percent-t962.html

I would really appreciate your time. My test is in a week and I hope to get a response before that.

Thanks

[RonPurewal]

Hi Tim,

I have 2 questions - regarding this particular qs and regarding argument type percentages vs numbers.

Regarding the above question, I chose D.

Since the question was based on the 3% stat, I figured the correct answer may revolve around the actual number of people who retired. So this thinking got me down to choices C & D. I picked D for the following reasoning,

conclusion: decrease in influx % --> -ve impact on eco of Florida
choice D: increase in people leaving --> -ve impact on eco of Florida

hmm? how do you get "increase in people leaving"?

according to choice (d), there will be more people entering florida, not leaving it. (perhaps the root of the problem lies in your interpretation of "another state". that doesn't mean another state besides florida; that means a state different from the state in which the person worked before retirement.)

i.e. conclusion: A --> B
choice D: C --> B

nope.

1/ this structure doesn't occur in choice (d); see above.

2/ even if it did, "c --> b" doesn't weaken "a --> b".
this template has no validity at all, ever. lots and lots of things have multiple causes; the presence of other possible causes in no way weakens the fact that "a" can cause "b".
for instance:
jumping from a 50-story building will cause death.
if i tell you drinking lye will also cause death, this obviously does not weaken the original statement.

also -- trying to memorize ANY kind of "template" for strengthen/weaken is a
very, very bad idea. not only will such an attempt be futile, but it will also impede your ability to THINK about problems that do not conform to the template (i.e., 99.99999% of problems that you will ever see).

I rejected choice C because it didn't talk about Florida.

hmm? florida is in choice (c).

do note, however, that the correct answer to strengthen/weaken choices must be outside the scope of the original argument!
you can't just repeat information from within the argument; it's impossible to strengthen or weaken an argument with things that are already in it.

Is it safe to say that if the premise of the argument is based on percentages vs numbers,

xxxxxxxxxxxxxxx

in such problems, just watch out for passages and choices that confuse percentages with absolute numbers; this type of confusion is a rather common theme in cr.

don't try to be more specific with "templates"; in cr, trying to memorize specific templates will actually make you do worse (especially on strengthen/weaken).

[georgepaul0071987]

Ron ,

Couldn't (D) also be wrong ?

I mean ,this answer choice just says that the total number of people who retired and moved to another state has increased , but we don’t know for sure that the number of people who retired and moved specifically to Florida has increased or not.

The same question was asked in one of the Thursdays with Ron video in which this problem was discussed . But I still wasn't too clear on why this analysis is incorrect .

Is this analysis incorrect because the correct answer in strengthen/weaken question only needs to "slightly" strengthen/weaken the argument as opposed to "completely confirm/destroy " the argument ?

[RonPurewal]

Ron ,

Couldn't (D) also be wrong ?

first --
OFFICIALLY CORRECT ANSWERS ARE CORRECT!
do not question officially correct answers!
far too many students on this forum make the mistake of questioning the correct answers; please note that doing so is a complete waste of your time and effort. i.e., exactly 0% of the time that you spend posting "isn't this official answer wrong?" is productive, and exactly 100% of that time is wasted.

"is this correct?" is never a productive question to ask about one of GMAC's correct answers. the answer is always yes.
"is this wrong?" / "is this X type of error?" is never a productive question to ask about one of GMAC's correct answers. the answer is always no.

instead, the questions you should be asking about correct official answers, if you don't understand them, are:
"why is this correct?"
"how does this work?"
"what understanding am i lacking that i need to understand this choice?"

this is a small, but hugely significant, change to your way of thinking.
you will suddenly find it much easier to understand the format, style, and conventions of the official problems if you retire the idea that they might be wrong.

Is this analysis incorrect because the correct answer in strengthen/weaken question only needs to "slightly" strengthen/weaken the argument as opposed to "completely confirm/destroy " the argument ?

no, in this case it's absolutely essential.

think about the percentage in the first sentence of the argument. mathematically, that's
100% x (people who moved to florida)/(people who moved between any two states)
statement (d) says that the denominator of this percentage has increased markedly. it should be clear that this statement is not insignificant.

[zeal4mba]

Thanks so much Ron, perfect way to think mathematically :)

no, in this case it's absolutely essential.

think about the percentage in the first sentence of the argument. mathematically, that's
100% x (people who moved to florida)/(people who moved between any two states)
statement (d) says that the denominator of this percentage has increased markedly. it should be clear that this statement is not insignificant.[/quote]

[RonPurewal]

You're welcome, but, hopefully, you don't have to think explicitly about mathematical constructs. If you have the right mentality, you should be able to think intuitively instead.

E.g.,
Ten years ago, 50% of families with teenagers in our town buy potato chips. Now, 60% of families with teenagers in this town buy potato chips. I guess more families here must be buying potato chips.
--> "What if there are fewer families with teenagers?" Hopefully, you don't have to think about literal fractions to have this thought. (If you do, you should try to get to a place where you don't anymore.)

[lsyang1212]

I just read this post about how to think of this CR problem in a more "mathematical" manner, and it totally helped, thank you!

I know this is the forum for GMAT Prep questions, but just as a reference, there is a question in OG13, CR #87 that is almost EXACTLY the same as this question, and I couldn't understand it for the life of me. This "mathematical" approach helped me figure it out.

Thanks again!

[RonPurewal]

You're welcome.

[RonPurewal]

You might also benefit from noticing that the treatment of statistics in CR is a complement to the treatment of statistics in the quant section.

Namely:

- In the quant section, you manipulate statistics. You do math with things like percentages, ratios, and rates, in many ways.
But you don't ever think about why you might use such units (as opposed to other units). Nor do you think about possible interpretations, or misinterpretations, of them. They're basically just random numerical values for you to push around a page according to set rules.

"- In CR, when statistics are present, you need to think about WHY those particular statistics have been chosen. The problem will usually revolve in some way around what those statistics do or don't represent, and about how they may or may not agree with a given interpretation.

[lsyang1212]

*heavy sigh* ok, I have a follow up question. As I examine my CAT results, it seems like the CR problems I am missing the most are the ones that have numbers/statistics/math in it. For example, Solve The Discrepancy problems are difficult for me.

I understand why the arguments may be flawed, and what kind of statement we need to make the argument work better (for any kind of question stem), but when there's math/averages/percents involved in a CR question, the answer choices all look somewhat OK to me, with no clear answer showing up. I try to personalize the situation (put myself in the scenario), predict an answer before looking at the answer choices, but there just seems to be a lot of "white noise" when I read the answer choices, making it difficult to choose the correct answer.

When I review what the correct answer is after the CAT exam, some of them I get, some of them I'm still confused on.

How do I get better at these CR questions that are sort of disguised as math questions? Do I just need to get better at math?

A little discouraged, but still giving this test all I've got.

P.S. I tend to get all the 600-700 level CR, RC, and SC questions right. It's the 700-800 level questions that get me.

P.P.S. CAT #2 score = 660 (Q44, V36), CAT #3 score = 640 (Q 42, V35). Aiming for a 680-700.

[RonPurewal]

My best answer to your question is actually contained in the post directly above yours. It's the paragraph beginning with "In CR, when statistics are present..."

You most certainly do not "have to get better at math". If you can tell that, say, 10 is greater than 7, that's about the limit of the actual math you'll have to do on CR.
Problems with non-trivial math appear in ... you guessed it ... the quant section.

It's a question of interpretation and meaning (like everything in the verbal section, really).
There's a pretty broad cross-section of "CR problems with statistics" out there. If you understand HOW and WHY the statistics in them are used, then your understanding should be more than adequate.

[RonPurewal]

By the way, I've done a few videos centered on "CR problems with statistics" here:
http://www.manhattangmat.com/thursdays-with-ron.cfm

If you search the page for the word "statistics", you'll find a few videos, at least two or three of which are CR-related.