OG10 inference - expert comment please

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OG10 inference - expert comment please

by GMATMadeEasy » Mon Jun 20, 2011 2:26 pm
Laws requiring the use of headlights during daylight hours can prevent automobile collisions. However, since daylight visibility is worse in countries farther from the equator, any such laws would obviously be more effective in preventing collisions in those countries. In fact, the only countries that actually have such laws are farther from the equator than is the continental United States.

Which of the following conclusions could be most properly drawn from the information given above?
(A) Drivers in the continental United States who used their headlights during the day would be just as likely to become involved in a collision as would drivers who did not use their headlights.
(B) In many countries that are farther from the equator than is the continental United States, poor daylight visibility is the single most important factor in automobile collisions.
(C) The proportion of automobile collisions that occur in the daytime is greater in the continental United States than in the countries that have daytime headlight laws.

(D) Fewer automobile collisions probably occur each year in countries that have daytime headlight laws than occur within the continental United States.
(E) Daytime headlight laws would probably do less to prevent automobile collisions in the continental United States than they do in the countries that have the laws.

OA is E and sounds good. Bit Isn't D is also fine ? expert please

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by David@VeritasPrep » Mon Jun 20, 2011 4:52 pm
Here is the problem with answer choice D...We know that the very reason for daytime headlight laws is because visibility is worse in those countries that have these laws. In fact, the laws are in place in order to try to prevent collisions.

Now D says "Fewer automobile collisions probably occur each year in countries that have daytime headlight laws than occur within the continental United States." Now how can you say that this must be true? The reason these places have these laws is because of the poor visibility. Did these laws work so well that now these places have fewer accidents?
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by GMATMadeEasy » Tue Jun 21, 2011 1:13 am
Thanks David. I am doing ok in Must be True question but sometimes I take more time to analyze I suppose. Like in this uestion, I analyzed C also for more than reuired time until I was convinced that it can NOT be true . partially it could be because ,under time pressure, I missed E and continued convincing myself that either C or D is correct.

Could I remove D by simply saying that no absolute figures' comparison can be deduced based on this (OG explanation is no DATA is given to concluse this)

Almost same is true for C to remove.

let me ask you a different question: How could we remove a bit aggresively in difficult MUST be true answer choice question ? I remmeber reading, long back, one of your posts about a GMATprep question in which it asks to infer for some parcel that are delivered on a particular day etc. i can find that question if you need.

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by sushbis » Tue Jun 21, 2011 8:26 am
E is the answer because none of the other options are supported by any premises/facts in the argument. Any extra inference in the answer options should always be discarded :- Thumb Rule

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by David@VeritasPrep » Tue Jun 21, 2011 1:08 pm
For me the quickest way to eliminate answer choices for a MUST BE TRUE type of question is to get rid of those that are out of scope as well as those that are Predictions. These two categories cover most all of the incorrect answers.

For out of scope I just use a little phrase - I ask myself "what does the stimulus say about (and then insert the subject of the answer choice)."

So for choice D, "what does the stimulus say about the relative number of collisions in various countries?" The answer is that the stimulus provides NOTHING on this subject. We do not know if there are more crashes farther north or not. Having driven a car in Puerto Rico and Mexico and ridden in a car in Central American countries I can tell you that I am surprised to have survived. I hear that this is true in many of the more tropical places, South America, the Middle East, Asia. So maybe those places have lots of crashes! But the stimulus is all that counts here. Be very aggressive. For an answer choice to be correct on a MUST BE TRUE the stimulus needs to have nearly said it word for word - a little variation is okay, but it must be very close. In this case there is nothing on the rates of crashes in various countries.

Same thing on choice C, nearly exactly the same. Here we are to compare proportions of collisions during the day in the U.S. versus some other countries. You have no basis for this! Be aggressive - this choice is gone immediately! We do not know the proportion of crashes in the day versus night for any country. So we cannot say that C is true.
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by Sanjay2706 » Tue Jun 21, 2011 10:21 pm
Great Explanation by David.
I went for E as well.

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by Ian Stewart » Tue Jun 21, 2011 11:06 pm
Answer D doesn't even talk about the *proportion* of collisions in each country - it talks about the absolute *number* of collisions in each country. Surely there are all kinds of factors besides headlight laws that determine the *number* of collisions each year in a country - the number of cars driving around, for one. The stem gives us no information about that, so we can't draw any conclusions about the actual number of collisions anywhere.
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by GMATMadeEasy » Wed Jun 22, 2011 1:02 am
@David - Thanks for great reply. Let me apply this (in aggresive manner) to some hard new uestions if i can find under timed conditions.Alos, I am curoius to check the same to the parcel question i mentioned. will get back to thsame thread in few days maximum.

@Ian - Thanks . You are right in saying that it does not even talk about proportions. I notcied the fact while reviewing. Sometimes, I try to generalize it so I can apply the strategy to other questions.

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by GMATMadeEasy » Wed Jun 22, 2011 4:02 am
@David and ian : On a second thought, the presence of Probably in answer choice D enticed me to choose it under time constraint. But this word itself kills the sole purpose of Must be true question.this is a new realisation - when a probable condition is stated probable in MUST be true question, ignore it. :)

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by Ian Stewart » Wed Jun 22, 2011 4:21 am
GMATMadeEasy wrote:@David and ian : On a second thought, the presence of Probably in answer choice D enticed me to choose it under time constraint. But this word itself kills the sole purpose of Must be true question.this is a new realisation - when a probable condition is stated probable in MUST be true question, ignore it. :)
Be careful here:

GMATMadeEasy wrote:
(E) Daytime headlight laws would probably do less to prevent automobile collisions in the continental United States than they do in the countries that have the laws.

OA is E
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by GMATMadeEasy » Wed Jun 22, 2011 5:51 am
ohh thanks.. ahh, i should say the highest probability one is the winner :).

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by David@VeritasPrep » Wed Jun 22, 2011 6:43 pm
GMATMadeEasy -

I would say that you have it backwards. Conditional words like "maybe" and "probably" was well as "some" and others can actually make it easier for something to be the correct answer to a inference/ conclusion type of question.

Which is easier to prove as true - "You will score over 700 in the next 30 days on the GMAT"

or

"You may eventually do well on the GMAT."

It is the absolute statements that can be harder to prove.
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by conquistador » Tue Sep 01, 2015 1:14 am
This is a repeated question in below link.

https://www.beatthegmat.com/laws-requiri ... 14934.html