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# In testing for food allergies, a false positive result

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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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20 Sep 2012, 09:58
OA is A.
False Negative result means the person is allergic but tested negative which means he can consume allergic food which could be life threatening.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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Updated on: 21 Sep 2012, 06:15

Goal -> To accurately determine food allergies

Plan -> physician must choose a test that gives a smallest % of false negative results.

Conclusion -> To achieve our goal, we must implement the above mentioned plan.

Conclusion indicates accurate determination of food allergies has something to do with false negative results.That is , it is not depending on false positive results.

As per the scope of the argument -> food allergy test may depend on false positive and false negative results and not on any other results.

Any statement, that confirms false positive results are not used/ need not be considered & only false negative reports are used to achieve the goal (to accurately determine food allergies) is the correct answer.

a. Talks abouts effects of food allergies, we require something about false negative results and how they can help in accurately determining the food allergy . Hence it doesnot effect the conclusion.

b. Here too, we are not concerned with the side effects of tests. This does not help us in accurately determining food allergy.Hence it doesnot effect the conclusion

d. proportion of unclear results doesnot give us any info about false poitive or false negative results. Without those, we cannot accurately determine the food allergies.

c. May be ! lets see in detail

This answer choice if taken as true means, most people have undiscovered allergies, so they are not aware of some of their own undiscovered allergies and hence may say they are not allergic to a particular food, where as they actually are allergic to that food. So they generate a false negative result. Most people are not aware of their own undiscovered allergies, so most people generate High number of false negative reports. But the answe choice says "It is important to be thorough" , so if people have information about their undiscovered allergies, they will not generate a false negative report. Seems good !

But wait, does it tell anything about " false postive results are not required / not considered " No !

we are left out E -> So, E is the correct answer !. Lets see how !

Tests consist of only flase positive and false negative results as per the argument. The answer choice says false positive results are constant across all tests. This means only false negatives help in determining the accuracy !.

Now say we have test 1 and test 2

test 1 - 10 false positive results and 3 false negative results
test 2 - 10 false positive results (since false positive result remain constant) and 7 false negative results.

Clearly test2 has low num of false negative results and more accurately determines the food allergy ! This supports our conclusion !

We can confirm this by negations .

Not all tests for food allergies have same proportions of false positive results. This means determining the accuracy of food allergy depends on both false positive and negative results. This breaks our conclusion which says accuracy depends only on false negative results. Since it breaks the conclusion on negation, this is the correct answer !

Originally posted by igloo on 20 Sep 2012, 10:09.
Last edited by igloo on 21 Sep 2012, 06:15, edited 3 times in total.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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20 Sep 2012, 10:16
I will choose option E.

Which of the following best completes the passage below:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, they are not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, they are. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because ______________________.

(A)Some food allergies cause reactions severe enough to be life-threatening. - This may be true but irrelevent to the question

(B) None of the tests for food allergies have lasting side effects. - The question is not about the effects or side effects - irrelevent

(C) In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies. - test is about finding the allergy only - other way to say the presmises.

(D) The proportion of tests that do not provide a clear result is the same for all tests of food allergies. - if this is true than there is no such test with smallest percentage of false negative results.

(E) All tests for food allergies have the same proportion of false positive results.[/quote] - Looks okay. if test has equal proportions of positive and negative, choose test which gives smaller %age of false negative.

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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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20 Sep 2012, 10:25
Answer is E , if the false positives are all same level , the test with least false negative will be the most accurate
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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20 Sep 2012, 13:07
The answer should be E, as it gives a comparison between positive and negative tests...going with the tone of the statement
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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20 Sep 2012, 23:02
Which of the following best completes the passage below:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, they are not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, they are. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because ______________________.

(A) Some food allergies cause reactions severe enough to be life-threatening.

(B) None of the tests for food allergies have lasting side effects.

(C) In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies.

(D) The proportion of tests that do not provide a clear result is the same for all tests of food allergies.

(E) All tests for food allergies have the same proportion of false positive results.

Analysis of passage: False positive results occur when a non-allergic person is falsely identified as allergic and a false negative result occurs when an allergic person is not identified as allergic.

Best answer is the one which expresses the importance false negative result as we should be concerned about the allergic person and therefore, to most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because some food allergies cause reactions severe enough to be life threatening.

B: If none of the tests have lasting side effects, the false negative or false positive results will be irrelevant.

C.: It talks about other undiscovered food allergies, which is irrelevant in the context.

D. We are not concerned about proportion of tests that do not provide a clear result because some severe allergies are required to be identified to enable physician to treat the patient.

E.: All tests for food allergies have the same proportion of false positive results but how the physician is going to most accurately determine the food allergies.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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20 Sep 2012, 23:45
Which of the following best completes the passage below:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, they are not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, they are. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because ______________________.

(A) Some food allergies cause reactions severe enough to be life-threatening.

(B) None of the tests for food allergies have lasting side effects.

(C) In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies.

(D) The proportion of tests that do not provide a clear result is the same for all tests of food allergies.

(E) All tests for food allergies have the same proportion of false positive results.

Ans:E , because to most accurately determine food allergies. You should have minimum of both false positive and false negative tests. As conclusion says "most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results" so the assumption is false positive tests have same proportion or it can't be improved. That's what E says
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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21 Sep 2012, 01:37
the premise -

1. Every type of Food allergy tests result in --> false positive & false negative

the conclusion -
2. A test with low of false negative % should be selected.

Reasoning -

Each test has two types of result sets (false +ve & false -ve ) and hence choosing the test will be based on the ratio of both the results. As the conclusion only talks about false negative we can not conclude whether the test with low false -ve is the best or not until we know the proportion of false +ve.

Or else - if we know that all tests will give the same % of False +ve then we can conclude that the test with low false -ve should be chosen.

lets see what each answer choice say-

(A) Some food allergies cause reactions severe enough to be life-threatening. - There is no mention of life-threat in the premise / Out of scope

(B) None of the tests for food allergies have lasting side effects. - There is no mention of duration of side effects / Out of scope

(C) In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies. - no mention of other food allergies in the premise / out of scope

(D) The proportion of tests that do not provide a clear result is the same for all tests of food allergies. - there is no mention of in conclusive results / Out of scope

(E) All tests for food allergies have the same proportion of false positive results. - Best answer
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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21 Sep 2012, 02:35

Reason: All tests same proportion of positive result means the doctor should choose the test with lowest false negative result.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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Updated on: 21 Sep 2012, 03:18

Since all the tests have same proportion of false positive result, so in order to determine the most accurate test results, physicians should use the test that gives the smallest percentage of false negative results.

I just tried to fit the answer choice in the argument.

Originally posted by bijoydinanath on 21 Sep 2012, 02:38.
Last edited by bijoydinanath on 21 Sep 2012, 03:18, edited 1 time in total.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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21 Sep 2012, 02:49
E

Since all tests for food allergies have the same proportion of false positive results, only smallest percentage of false negative results will give the most accurate result.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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21 Sep 2012, 07:37
bb wrote:

Veritas Prep 10 Year Anniversary Promo Question #8 Critical Reasoning

One quant and one verbal question will be posted each day starting on Monday Sept 17th at 10 AM PST/1 PM EST and the first person to correctly answer the question and show how they arrived at the answer will win a free Veritas Prep GMAT course (\$1,650 value). Winners will be selected and notified by a GMAT Club moderator. For more questions and details please check here: veritas-prep-10-year-anniversary-giveaway-138806.html

To participate, please make sure you provide the correct answer (A,B,C,D,E) and explanation that clearly shows how you arrived at it.
Winners will be announced the following day at 10 AM Pacific/1 PM Eastern Time.

Good Luck! May the best and fastest win!

Which of the following best completes the passage below:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, they are not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, they are. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because ______________________.

(A) Some food allergies cause reactions severe enough to be life-threatening.

(B) None of the tests for food allergies have lasting side effects.

(C) In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies.

(D) The proportion of tests that do not provide a clear result is the same for all tests of food allergies.

(E) All tests for food allergies have the same proportion of false positive results.

Winner of the contest is geno5

Here is the OE

Solution: E. This question illustrates a couple of critical concepts for Critical Reasoning. First it introduces you to the "Best Completes the Passage" format, in which you need to infer the question stem from the language immediately preceding the underlined portion-to-be-completed. Here that word is "because", which seeks evidence for a conclusion. And that conclusion is "in order to most accurately determine food allergies, doctors should use the test with the smallest percentage of false negatives". The goal in this question is clearly to strengthen that conclusion.

With this in mind, you are now set up for another common trap- one in which the author of the question knows where your mind wants to go, and baits you in that direction. When you think of an allergy (or really any medical) diagnosis, what is your biggest fear? Probably that the doctor will miss a diagnosis and allow you to continue with a risky behavior that could negatively affect your quality of life. Say, for example, that you are allergic to peanuts, but your doctor falsely (false negative) says that you're not. Your next peanut butter sandwich could be catastrophic! On the flip side, if the doctor tells you that you are allergic to peanuts when it turns out you're not, that's more of an inconvenience than anything. It's a bummer to not enjoy Reese's peanut butter cups, but it's not life-threatening.

So, naturally, your mind wants to minimize false negatives, to err on the side of safety. But what's the conclusion? To most accurately (not most safely!) determine allergies, you should eliminate false negatives. For this specific objective, false positives are just as detrimental as false negatives – each is inaccurate. And so the correct answer needs to give you some reason why you are only focusing on false negatives if the goal is accuracy. Choice E, which does not bear on safety (but neither does the conclusion) is correct, as it shows that false positives will be the same for each test, so the only way to become more accurate is to minimize false negatives.

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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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21 Sep 2012, 08:17
Thanks, BB and Veritas Gmatclub is great! Do not know what I would do without it! Good luck to todays contestants.
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Re: Veritas Prep 10 Year Anniversary Promo Question #8  [#permalink]

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21 Sep 2012, 08:24
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Congratulations Geno5!

P.S. This question winner was determined by one of the Verbal Moderators, souvik101990, and I can tell you he did put a lot of thinking into the decision and so did I. Your victory is well deserved - Kudos for your perseverance. You have come very close on many questions and it is great to see you win.

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Re: In testing for food allergies, a false positive result  [#permalink]

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21 Dec 2014, 08:46
Souvik - Can you please provide an explanation to this. I thought the OA is C

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Re: In testing for food allergies, a false positive result  [#permalink]

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30 Dec 2014, 03:29
3
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, he is not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, he is. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because _________________________

A. some food allergies cause reactions severe enough to be life-threatening
B. none of the tests for food allergies have lasting side effects
C. in diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies
D. the proportion of tests that do not provide a clear result is the same for all tests of food allergies
E. all tests for food allergies have the same proportion of false positive results

rohit

As the argument states that in order to determine food allergy a physician should use the test that gives smallest percentage of false negative result, so we need to find a statement which help us in showing that all tests have same rate of false positive result because if all the tests are at par on false positive results than it make sense to use the test that gives smallest percentage of false negative result.

Hope this helps.

Press kudos if the post is useful.
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Re: In testing for food allergies, a false positive result  [#permalink]

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31 Dec 2014, 00:20
E) seems justifiable, since the proportion of false positive for all test is the same, indicating the one with smallest percentage of false negative will also have smallest percentage of false positives. In other-words, that test would be the most accurate.

But, A (some food allergies cause reactions severe enough to be life-threatening) also seems pretty compelling since it says that it would be better to have test that has False positive than to have test that have higher False negatives, implying that if a person (allergic to a food and is not diagnosed correctly(in case of false negative)) consumes a food, to which he is allergic, based on the report, the result could be fatal.

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In testing for food allergies, a false positive result  [#permalink]

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03 Jan 2015, 21:47
3
souvik101990 wrote:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, he is not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, he is. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because _________________________

A. some food allergies cause reactions severe enough to be life-threatening
B. none of the tests for food allergies have lasting side effects
C. in diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies
D. the proportion of tests that do not provide a clear result is the same for all tests of food allergies
E. all tests for food allergies have the same proportion of false positive results

To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results because _________________________

THE MOST ACCURATE TEST WILL BE - MIN false positive( X) + MIN false negative( Y)

X + Y has to be minimum......
If Y IS CONSTANT ie MIN false negative( Y) is constant ..........
The best test ie best min error test will be one which has MINIMUM X ie MIN false positive( X)

E. all tests for food allergies have the same proportion of false positive results....

REGARDS and Happy New Year to all GMAT CLUBBERS.......
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Re: In testing for food allergies, a false positive result  [#permalink]

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07 May 2015, 09:08
I'm not entirely clear why it cannot be A??

gmatter0913 wrote:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, they are not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, they are. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results.

Which of the following, if true, most supports the recommendation that is given above?

A. Some food allergies cause reactions severe enough to be life-threatening.
B. None of the tests for food allergies have lasting side effects.
C. In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies.
D. The proportion of tests that do not provide a clear result is the same for all tests of food allergies
E. All tests for food allergies have the same proportion of false positive results
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Re: In testing for food allergies, a false positive result  [#permalink]

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07 May 2015, 11:08
1
Hi Kevin,

Upon further thinking, I understood the answer is E.

Because as follows..

Options B, C and D are clearly not relevant.

Option A: Small sample can give a life threatning reaction. The study is using False Negative approach that is patients who think they are allergic but in fact are not allergic. The word 'Some' plays a crucial role. This means there are some substance that do not give any life threatening reactions, and perhaps when tested in the False + method, the patient may not show allergic reaction (because the patient is not allergic.)

Option E: Using the False Negative theory: That is patient think he is not allergice but actually is allergic. Hence the physician can accurately test the sample. Purely because the patient is allergic, the patient will develop reaction and hence testing.

Hope this helps.

kelvind13 wrote:
I'm not entirely clear why it cannot be A??

gmatter0913 wrote:
In testing for food allergies, a false positive result occurs when a person is said to be allergic to a particular food when, in fact, they are not allergic to that food. A false negative result indicates that a person is not allergic to the food when, in fact, they are. To most accurately determine food allergies, a physician should use the test that gives the smallest percentage of false negative results.

Which of the following, if true, most supports the recommendation that is given above?

A. Some food allergies cause reactions severe enough to be life-threatening.
B. None of the tests for food allergies have lasting side effects.
C. In diagnosing food allergies it is important to be as thorough as possible, since most people with one known food allergy have other undiscovered food allergies.
D. The proportion of tests that do not provide a clear result is the same for all tests of food allergies
E. All tests for food allergies have the same proportion of false positive results

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Re: In testing for food allergies, a false positive result &nbs [#permalink] 07 May 2015, 11:08

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