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GMATPrep - Strenthen (An answer choice a common trap)

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GMATPrep - Strenthen (An answer choice a common trap)

by GMATMadeEasy » Thu May 12, 2011 4:57 am
In parts of South America, vitamin-A deficiency is a serious health problem, especially among children. In one region, agriculturists hope to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in betacarotene, which the body converts into vitamin A. The plan has good chances of success, since sweet potato is a staple of the region's diet and agriculture, and the varieties currently grown contain little beta-carotene.

which of the following, if true, most strongly supports the prediction that the plan will succeed?

a. There are other vegetables currently grown in the region that contain more beta-carotene than the currently cultivated varieties of sweet potato do.
b. The flesh of SPK004 differs from that of the currently cultivated sweet potatoes in colors and textures, so traditional foods would look somewhat different when prepared from SPK004.
c. For successful cultivation of SPK004, a soil significantly richer in nitrogen is needed than is needed for the varieties of sweet potato currently cultivated in the region.
d. There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.
e. the currently cultivated varieties of sweet potato contain no important nutrients that SPK004 lacks.

OA is E.

A, B and C are clearly out.

Question is about D . Is it wrong because the argument already mentiones that "the varieties currently grown contain little beta-carotene" and choice D says the same thing in different words.
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by maihuna » Thu May 12, 2011 5:32 am
Yes now doubt D looks close but still far, what if there are other varieties that contains more betecarotene, is the amount to a certain extent an requirement, clearly no. So we do not necessarily needs D to be true.
GMATMadeEasy wrote:In parts of South America, vitamin-A deficiency is a serious health problem, especially among children. In one region, agriculturists hope to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in betacarotene, which the body converts into vitamin A. The plan has good chances of success, since sweet potato is a staple of the region's diet and agriculture, and the varieties currently grown contain little beta-carotene.

which of the following, if true, most strongly supports the prediction that the plan will succeed?

a. There are other vegetables currently grown in the region that contain more beta-carotene than the currently cultivated varieties of sweet potato do.
b. The flesh of SPK004 differs from that of the currently cultivated sweet potatoes in colors and textures, so traditional foods would look somewhat different when prepared from SPK004.
c. For successful cultivation of SPK004, a soil significantly richer in nitrogen is needed than is needed for the varieties of sweet potato currently cultivated in the region.
d. There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.
e. the currently cultivated varieties of sweet potato contain no important nutrients that SPK004 lacks.

OA is E.

A, B and C are clearly out.

Question is about D . Is it wrong because the argument already mentiones that "the varieties currently grown contain little beta-carotene" and choice D says the same thing in different words.
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by atulmangal » Thu May 12, 2011 6:36 am
Man, this is tricky, i picked Op D and that's wrong...

I mean Op D can be the answer if question stem asks us to draw an inference, m sure, in that case Op D is the only best answer. Lesson learned, in case of strengthen / weaken questions, the op which is a rephrase of premise is wrong.
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by Brent@GMATPrepNow » Thu May 12, 2011 7:04 am
Let's take a closer look at the argument.

The goal is to "improve nutrition."
To do this, agriculturists plan to encourage farmers to plant a new type of sweet potato.
The conclusion is that the plan has good chances of success.
In other words, the plan will improve people's nutrition in the area.

For strengthen question, we can negate the answer choices. The negation that hurts the argument the most will indicate the correct answer. (I'll skip A, B and C, since everyone seems to agree that these are not correct).

Negating D: There ARE other varieties of sweet potato that significantly are richer in beta-carotene.
Does the negation of answer choice D hurt the argument?
No. Since SPK004 is already "rich in betacarotene," the people's nutrition will still improve

Negating E: The currently cultivated varieties of sweet potato DO contain important nutrients that SPK004 lacks.
Does the negation of answer choice E hurt the argument?
Yes. The goal is to improve nutrition. Sure, SPK004 will improve people's level of vitamin A, but the people will then lack other "important" nutrients that are in the current variety of sweet potato. So, people's nutrition may actually get worse with the plan.

Since the negation of E hurts argument more than the negation of D, the answer is E.

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by GMATMadeEasy » Fri May 13, 2011 2:00 am
@Negating D:
There ARE other varieties of sweet potato that significantly are richer in beta-carotene.
Does the negation of answer choice D hurt the argument?
No. Since SPK004 is already "rich in betacarotene," the people's nutrition will still improve
Brent to cofnirm the logic: I agree D is wrong but ,I beleive, not for the reaons staed as above. Could you plase clarify .

Your negation: There are other varities of sweet potatos, that are significantly higher in betacarotine . , then it is possible that those people will grow other sweet potatoes as they have clear advantage of significantly more betacarotine. .. why not ? at this moment, we do not know anything about cost difference or anything among these varities.

Your thoughts please.
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by vikram4689 » Fri May 13, 2011 8:14 am
Hi Brent,

Even i feel some problems with negation technique for D.

Negation for D: There ARE some varieties richer in B-Carotene than SKH004.
Now if there are varieties and still nutrition problem is there then introducing a variety (SKH004) with lower B-carotene would not be able to alleviate the problem. So it hurts the argument.
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by GMATMadeEasy » Fri May 13, 2011 8:25 am
vikram4689 wrote:Hi Brent,

Even i feel some problems with negation technique for D.

Negation for D: There ARE some varieties richer in B-Carotene than SKH004.
Now if there are varieties and still nutrition problem is there then introducing a variety (SKH004) with lower B-carotene would not be able to alleviate the problem. So it hurts the argument.
I believe you are misinterpreting here a little. It is stated in the argument that it is rich in betacarotine (BC) . Question now one can raise is :

If there are other varieties of potatoes much richer than potato under discussion and those varieties are adopted instead of the one mentioned in the argument, in any case our goal -- to improve nutrition by encouraging farmers to plant a new variety of sweet potato -- is achieved.

In other words, if there is an answer choice that proposes an alternative to achieve the same thing differently but more efficiently than the way suggested in argument, how should one treat this ? It strengthens the argument by achieving its stated goal ? weakens because it is not achieved the way it was intended in the argument? may be this will NOT happen in the real exam. a thought.

need help here please.
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by Brent@GMATPrepNow » Fri May 13, 2011 8:36 am
GMATMadeEasy wrote:@Negating D:
There ARE other varieties of sweet potato that significantly are richer in beta-carotene.
Does the negation of answer choice D hurt the argument?
No. Since SPK004 is already "rich in betacarotene," the people's nutrition will still improve
Brent to cofnirm the logic: I agree D is wrong but ,I beleive, not for the reaons staed as above. Could you plase clarify .

Your negation: There are other varities of sweet potatos, that are significantly higher in betacarotine . , then it is possible that those people will grow other sweet potatoes as they have clear advantage of significantly more betacarotine. .. why not ? at this moment, we do not know anything about cost difference or anything among these varities.

Your thoughts please.
I think it's important to note that the goal is to improve nutrition.
This does not mean to improve nutrition to the greatest extent possible.
So, it seems that since the SPK004 is already "rich in betacarotene," the people's nutrition will improve.

Sure, there might be better varieties, but that doesn't mean the SPK004 potato won't improve nutrition.

I hope that helps.

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by Brent@GMATPrepNow » Fri May 13, 2011 8:41 am
vikram4689 wrote:Hi Brent,

Even i feel some problems with negation technique for D.

Negation for D: There ARE some varieties richer in B-Carotene than SKH004.
Now if there are varieties and still nutrition problem is there then introducing a variety (SKH004) with lower B-carotene would not be able to alleviate the problem. So it hurts the argument.
Oops, I had to edit my post, since I misread your point.

You're saying that it could be the case that the potatoes that are currently planted as already higher in B-carotene, in which case nutrition would be worsened if we replace them with the new SKH004 potato.

The only problem with this is that the passage states that "the varieties currently grown contain little beta-carotene."

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by vikram4689 » Fri May 13, 2011 8:50 am
So can i conclude that if negation of an option contradicts the fact/premise in argument then option cannot be correct. However if negation hurts a conclusion then option is correct.

Can you provide with a general rule that can be taken as a learning from this ques. Only doubt we all had is HOW TO PROVE THAT D is Incorrect
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by Brent@GMATPrepNow » Fri May 13, 2011 8:56 am
vikram4689 wrote:sry could not get this one,

if a variety with higher BC is NOT able to improve nutrition then
how a variety with lower BC will improve nutrition.

I mean SKP004 will not improve nutrition even by minimal amount.
The passage says that "the varieties currently grown contain little beta-carotene."
Since the SKP004 variety "is rich in betacarotene," nutrition should improve.

Sure, other possible varieties might contain more betacarotene, and nutrition could improve even more (if these varieties were planted). But this does not mean that the SKP004 will not improve nutrition.

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by vikram4689 » Fri May 13, 2011 9:13 am
seems we are replying almost the same time :) .... please answer my last query

So can i conclude that if negation of an option contradicts the fact/premise in argument then option cannot be correct. However if negation hurts a conclusion then option is correct.

Can you provide with a general rule that can be taken as a learning from this ques. Only doubt we all had is HOW TO PROVE THAT D is Incorrect
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by Brent@GMATPrepNow » Fri May 13, 2011 9:22 am
vikram4689 wrote:seems we are replying almost the same time :) .... please answer my last query

So can i conclude that if negation of an option contradicts the fact/premise in argument then option cannot be correct. However if negation hurts a conclusion then option is correct.

Can you provide with a general rule that can be taken as a learning from this ques. Only doubt we all had is HOW TO PROVE THAT D is Incorrect
For strengthen/assumption questions, we're looking for a new piece of information to make the argument better.

In other words, the argument needs the new information to be true.

So, if take a piece of required information (i.e., the correct answer) and negate it, then the negated statement should harm the argument (since the argument needed that info to be true)

So whatever negated info that harms the argument the most will be the correct answer.

In most cases, the incorrect answers (when negated) will have little or no affect on the argument.

Here, the negation of D does not affect the argument that the new potato will improve nutrition.

I hope that helps.

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by vikram4689 » Fri May 13, 2011 4:00 pm
Thanks....In case we are saying that negating D does not hurt the argument because negation of D contradicts a premise "current varieties have lower BC". So can i conclude that if negation of an option contradicts the fact/premise in argument then option cannot be correct. However if negation hurts a conclusion then option is correct.
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by atulmangal » Fri May 13, 2011 4:23 pm
vikram4689 wrote:Thanks....In case we are saying that negating D does not hurt the argument because negation of D contradicts a premise "current varieties have lower BC". So can i conclude that if negation of an option contradicts the fact/premise in argument then option cannot be correct. However if negation hurts a conclusion then option is correct.
This is not correct. if negation of the assumption hurts the main supporting premise (kind of sub-conclusion u say), then that assumption is also a valid assumption.

"agriculturists hope to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in betacarotene"

This is actually the tricky part of the argument. Initially argument starts with the issue related to the deficiency of VITAMIN A and certainly in this conclusion part, it talks about general NUTRITION not just VITAMIN A...that's why Bren state that goal is to improve nutrition not just VITAMIN A.

So, here the argument tricked us and change its emphasis from ONLY VITAMIN A to Other Nutrients + Vitamin A

If u negate Op D, u get other types contain lesser VITAMIN A...that's okay..it doesn't say, NO VITAMIN A...

But if u negate Op E, the use of strong word NO in this Op says...NO OTHER NUTRIENT APART FROM VITAMIN A IS THERE IN SPK004....this hurts the argument as we also need other nutrients too.
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