Mary Mallon, known as “Typhoid Mary,” was a typhoid “carrier”

Answer: E

Its between C and E.
C is wrong because its relating symptoms with typhoid fever. This does nothing to strengthen the claim since its talking about reliability so it may be true or false.
E is best because its relating typhoid bacillus with typhoid fever which is a closer parallel to the argument and strengthens the claim.

This is an inference question.

Option B suggest the equal probability of getting typh from those who got the bacteria and have the disease vs those who got the bacteria and dont have the disease. We can not infer this from just one instance.

Option C is a 180...Mary did not get the symptoms as well as the disease. C however talks about those who don't show the symptoms but still has the disease.

E correctly infers from the stimulus.

Mary Mallon, known as “Typhoid Mary,” was a typhoid “carrier” who was infected with the typhoid bacillus for a prolonged period of time, She developed neither the disease nor its symptoms; however, other people could, and did, develop this disease after contact with her.

Which of the following is best supported by the statements above?

A. Typhoid fever is not always fatal.

B. Typhoid fever is equally communicable whether the person infected with the typhoid bacillus actually has the disease or not.

C. The absence of the usual symptoms of typhoid fever is not always a reliable indicator that one does not have typhoid fever.

D. Typhoid fever sometimes occurs even when the typhoid bacillus is not present.

E. The typhoid bacillus does not always cause typhoid fever.

C seems more appropriate.

Could you give a detailed explanation as to why E is right?

The question looks incomplete as there is nothing mentioned in the statement that matches the OA.

Please give detailed explanation.

The stimulus mentioned that - she was infected with the typhoid bacillus, but she developed neither the disease nor its symptoms.
So, we can infer that the presence of typhoid bacillus do not always develop the disease or its symptoms. But, we can't infer that - the presence of the symptoms is the surest indicator of the disease, or vice versa.
So, we can see that C links fever and symptoms.. So eliminate C



The OA is correct and very well matches with the stated fact : she was infected with the typhoid bacillus, but she developed neither the disease nor its symptoms.
That means that there can be or can't be a causal connection, just that we are not sure of it. So, "does not always" in E is perfect.

I highly doubt that this is a sub 700 level problem...

Cheers !!

I agree with godot53. The statement doesn't establish a casual relationship

Mary Mallon, known as “Typhoid Mary,” was a typhoid “carrier” who was infected with the typhoid bacillus for a prolonged period of time. She developed neither typhoid fever nor its symptoms; however, other people could, and did, develop this disease after contact with her.

Which of the following is best supported by the statements above?

A. Typhoid fever is not always fatal. IRRELEVANT. nowhere mentioned in argument

B. Typhoid fever is equally communicable whether the person infected with the typhoid bacillus actually has the disease or not. IRRELEVANT. nowhere mentioned in argument that person with disease or not....

C. The absence of the usual symptoms of typhoid fever is not always a reliable indicator that one does not have typhoid fever. IRRELEVANT. reliable indicator is irrelevant

D. Typhoid fever sometimes occurs even when the typhoid bacillus is not present. IRRELEVANT. nowhere mentioned in argument

E. The typhoid bacillus does not always cause typhoid fever. This has relation to argument. Argument says that Mary Mallon was infected for a prolonged period of time, but not mentioned that she had typhod.
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Tricky question. Took me a bit to see the error in my analysis.

Mary has the bacteria, but does NOT have the fever. Although she can pass on the bacteria and give people the fever part of the disease, she does not show any symptoms of the fever.

(C) “The absence of the usual symptoms of typhoid fever is not always a reliable indicator that one does not have typhoid fever.”

Details, details, details.....


Mary has the bacteria. Mary does NOT have the fever.

So we are given a case in which the person shows no symptoms and does not have the fever.

From this case, we can’t tell anything about whether “no symptoms” is a bad proxy for “no fever.” All we can be sure of is that “no symptoms” does NOT always mean that a person does not have the BACTERIA.

We are not given a case in which someone has the fever part of it. It could be the case that an absence of symptoms IS a reliable indicator that one does not have the fever. After all, Mary isn’t showing symptoms. She doesn’t have the fever. Maybe the symptoms only show up when you have the fever and nothing occurs when you only have the bacteria.


E is the correct answer.

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Understanding the argument - ­
Mary Mallon, known as “Typhoid Mary,” was a typhoid “carrier” who was infected with the typhoid bacillus for a prolonged period of time. - Fact. 
She developed neither typhoid fever nor its symptoms; however, other people could, and did, develop this disease after contact with her. - Fact 

Option Elimination - Inference 

A. Typhoid fever is not always fatal. - Out of scope. 

B. Typhoid fever is equally communicable whether the person infected with the typhoid bacillus actually has the disease or not. - "A person not infected by "typhoid bacillus" is not discussed in the argument. Out of scope. 

C. The absence of the usual symptoms of typhoid fever is not always a reliable indicator that one does not have typhoid fever. - "Always" is hyperbolic. Moreover, it means that they may still have a "typhoid fever." But the passage doesn't discuss any case wherein the person had no symptoms but had a "typhoid fever." Isn't it? Mary's case has no symptoms and no typhoid fever. Out of scope. 

D. Typhoid fever sometimes occurs even when the typhoid bacillus is not present. - The case of "the typhoid bacillus not present" is not discussed. Mary's case has the "typhoid bacillus." Out of scope. 

E. The typhoid bacillus does not always cause typhoid fever. - Yes. This is Mary's case. 

This is an inference question and not a Flaw question.

­Chanaged the tag. Thank you.
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