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One test to determine whether a person has been infected with tubercul

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One test to determine whether a person has been infected with tubercul  [#permalink]

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17 Jul 2017, 08:09
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74% (02:12) correct 26% (02:13) wrong based on 412 sessions

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One test to determine whether a person has been infected with tuberculosis consists of injecting the person with proteins extracted from the tuberculosis bacterium. Once a person has been infected by a bacterium, the person’s immune system subsequently recognizes certain proteins present in that bacterium and attacks the bacterium. This recognition also takes place in the test and results in a skin irritation at the injection site. Hence the physicians who designed the test reasoned that anyone who reacts in this manner to an injection with the tuberculosis proteins has been infected with tuberculosis.

Which one of the following is an assumption on which the physicians’ reasoning depends?

(A) All of the proteins present in disease-causing bacteria can be recognized by the body’s immune system.

(B) Localized skin irritations are a characteristic symptom of tuberculosis in most people.

(C) The ability of the proteins present in the tuberculosis bacterium to trigger the skin irritation is exclusive to that bacterium.

(D) Some people who have been injected with proteins extracted from the tuberculosis bacterium will contract tuberculosis as a result of the injection.

(E) The body’s immune system cannot recognize infectious bacteria unless there are sufficient quantities of the bacteria to cause overt symptoms of disease.

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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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17 Jul 2017, 08:48
Akela wrote:
One test to determine whether a person has been infected with tuberculosis consists of injecting the person with proteins extracted from the tuberculosis bacterium. Once a person has been infected by a bacterium, the person’s immune system subsequently recognizes certain proteins present in that bacterium and attacks the bacterium. This recognition also takes place in the test and results in a skin irritation at the injection site. Hence the physicians who designed the test reasoned that anyone who reacts in this manner to an injection with the tuberculosis proteins has been infected with tuberculosis.

Which one of the following is an assumption on which the physicians’ reasoning depends?

(A) All of the proteins present in disease-causing bacteria can be recognized by the body’s immune system.

(B) Localized skin irritations are a characteristic symptom of tuberculosis in most people.

(C) The ability of the proteins present in the tuberculosis bacterium to trigger the skin irritation is exclusive to that bacterium.

(D) Some people who have been injected with proteins extracted from the tuberculosis bacterium will contract tuberculosis as a result of the injection.

(E) The body’s immune system cannot recognize infectious bacteria unless there are sufficient quantities of the bacteria to cause overt symptoms of disease.

Source: LSAT

HI..

lets see the reasoning of PARA
A person affected from tuberculosis if injected with proteins extracted from the BACTERIUM will result in skin irritations at the injected location

what could be the flaw in reasoning - No other event can lead to this type of irritation..
so this FLAW otherwise could be the VERY assumption the author has taken

C correctly rephrases the flaw and gives the assumption. If we negate it, the reasoning will fail as shown by flaw..
C
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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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17 Jul 2017, 18:52
Clearly as you read the para
You know that author is assuming skin irritation is caused only due to TB bacteria

C states that

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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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17 Jul 2017, 19:43
chetan2u wrote:
Akela wrote:
One test to determine whether a person has been infected with tuberculosis consists of injecting the person with proteins extracted from the tuberculosis bacterium. Once a person has been infected by a bacterium, the person’s immune system subsequently recognizes certain proteins present in that bacterium and attacks the bacterium. This recognition also takes place in the test and results in a skin irritation at the injection site. Hence the physicians who designed the test reasoned that anyone who reacts in this manner to an injection with the tuberculosis proteins has been infected with tuberculosis.

Which one of the following is an assumption on which the physicians’ reasoning depends?

(A) All of the proteins present in disease-causing bacteria can be recognized by the body’s immune system.

(B) Localized skin irritations are a characteristic symptom of tuberculosis in most people.

(C) The ability of the proteins present in the tuberculosis bacterium to trigger the skin irritation is exclusive to that bacterium.

(D) Some people who have been injected with proteins extracted from the tuberculosis bacterium will contract tuberculosis as a result of the injection.

(E) The body’s immune system cannot recognize infectious bacteria unless there are sufficient quantities of the bacteria to cause overt symptoms of disease.

Source: LSAT

HI..

lets see the reasoning of PARA
A person affected from tuberculosis if injected with proteins extracted from the BACTERIUM will result in skin irritations at the injected location

what could be the flaw in reasoning - No other event can lead to this type of irritation..
so this FLAW otherwise could be the VERY assumption the author has taken

C correctly rephrases the flaw and gives the assumption. If we negate it, the reasoning will fail as shown by flaw..
C

If A and B are negated, even then the conclusion fails to prove its point. Can you please explain why option A and B are incorrect answers to this question?
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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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18 Jul 2017, 08:27
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nk05 wrote:
Why is B wrong?

We're trying to find an assumption that backs up the following claim:

If a patient is injected with the tuberculosis protein AND that patient experiences a skin irritation at the injection site THEN they must have tuberculosis.

(A) All of the proteins present in disease-causing bacteria can be recognized by the body’s immune system. No mention of the skin irritation

(B) Localized skin irritations are a characteristic symptom of tuberculosis in most people. Vague mention of skin irritations and its effect on most people. This choice does not mention the tuberculosis protein being the root of the irritation but could be an irritation caused by anything.

(C) The ability of the proteins present in the tuberculosis bacterium to trigger the skin irritation is exclusive to that bacterium. Supports our If-Then statement that the irritation is caused exclusively by the injected tuberculosis protein

(D) Some people who have been injected with proteins extracted from the tuberculosis bacterium will contract tuberculosis as a result of the injection. Out of scope. There's no mention that the injection causes tuberculosis.

(E) The body’s immune system cannot recognize infectious bacteria unless there are sufficient quantities of the bacteria to cause overt symptoms of disease. Out of scope. Question is looking for an assumption around the protein injection and a skin irritation.
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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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08 Oct 2018, 21:41
use negation is option c
if it is not exclusive then it will weaken the conclusion.
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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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08 Oct 2018, 22:09
manjot123 wrote:
use negation is option c
if it is not exclusive then it will weaken the conclusion.
Absolutely, however,it will not weaken the conclusion but infact break it altogether.

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Please consider pressing Kudos if my response helped you in any way !
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Re: One test to determine whether a person has been infected with tubercul  [#permalink]

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28 Mar 2020, 04:03
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Re: One test to determine whether a person has been infected with tubercul   [#permalink] 28 Mar 2020, 04:03