Critical Reasoning - Discussions

[swati.pdh]

Hi Guys,

Try this one...A good question(perhaps ;) )



A researcher discovered that people who have low levels of immune system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.

The researcher's conclusion depends on which of the following assumptions?

(A) High immune-system activity protects against mental illness better than normal immune-system activity does.
(B) Mental illness is similar to physical disease in its effects on body systems.
(C) People with high immune-system activity cannot develop mental illness.
(D) Mental illness does not cause people's immune-system activity to decrease.
(E) Psychological treatment of mental illness is not as effective as is medical treatment.

[Matt P]

A researcher discovered that people who have low levels of immune system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.

The researcher's conclusion depends on which of the following assumptions?

(A) High immune-system activity protects against mental illness better than normal immune-system activity does.

Out of scope; normal and high are grouped together in the premise and thus for our purposes indistinguishable. 

(B) Mental illness is similar to physical disease in its effects on body systems.

Out of scope; there is no discussion of effects on body system. 

(C) People with high immune-system activity cannot develop mental illness.

Too extreme; definitely cannot be deduced. 

(D) Mental illness does not cause people's immune-system activity to decrease.

Correct. If mental illness caused the immune-system activity to decrease, then low immune-system activity would follow from mental illness, not the other way around, which is what the conclusion indicates. The conclusion implies that mental illness would follow from low immune-system activity.

(E) Psychological treatment of mental illness is not as effective as is medical treatment.

Out of scope. Nothing is said about medical treatment. 

[swati.pdh]

@Matt, Your ans is perfectly correct

[swati.pdh]

One more, This is a bit tricky(for me :) )


Bank depositors in the United States are all financially
protected against bank failure because the government
insures all individuals’ bank deposits. An economist
argues that this insurance is partly responsible for the
high rate of bank failures, since it removes from
depositors any financial incentive to fi nd out whether
the bank that holds their money is secure against
failure. If depositors were more selective, then banks
would need to be secure in order to compete for
depositors’ money.
The economist’s argument makes which of the
following assumptions?
(A) Bank failures are caused when big borrowers
default on loan repayments.
(B) A significant proportion of depositors maintain
accounts at several different banks.
(C) The more a depositor has to deposit, the more
careful he or she tends to be in selecting a bank.
(D) The difference in the interest rates paid to
depositors by different banks is not a significant
factor in bank failures.
(E) Potential depositors are able to determine which
banks are secure against failure.

[Matt P]

Bank depositors in the United States are all financially protected against bank failure because the government
insures all individuals’ bank deposits. An economist argues that this insurance is partly responsible for the

high rate of bank failures, since it removes from depositors any financial incentive to find out whether

the bank that holds their money is secure against failure. If depositors were more selective, then banks
would need to be secure in order to compete for depositors’ money.

The economist’s argument makes which of the following assumptions?

 

(A) Bank failures are caused when big borrowers default on loan repayments.

- Seems a bit out of scope; nothing was mentioned about 'big borrowers' 

(B) A significant proportion of depositors maintain accounts at several different banks.

- Out of scope / irrelevant. Plus, why would depositors do this if they're careless, as the premise implies?

(C) The more a depositor has to deposit, the more careful he or she tends to be in selecting a bank.

- Logical, but again out of scope. Nothing is said about the amount that someone wants to deposit. 

(D) The difference in the interest rates paid to depositors by different banks is not a significant factor in bank failures.

- Out of scope. We don't really care about the other factors. 

(E) Potential depositors are able to determine which banks are secure against failure.

- Perfect answer. The conclusion states that banks would need to be more secure to keep/gain customers. 

[swati.pdh]

Hey Matt,

That is the correct answer. But why option D is incorrect?
In assumption questions, if X->Y, we assume that there is no other reason that causes Y.

Here, insurance -> bank failures so should D be the ans which says that interest rates are not the reason.

Did you get my point?

[Matt P]

Hi Swati,

Ok - so we're trying to find an assumption that the author relies on. I.e, if the assumption isn't true, the argument doesn't work.

With that in mind, let's take a look at option D:

"The difference in the interest rates paid to depositors by different banks is not a significant factor in bank failures."

There is nothing in the argument, implicit or explicit, that has anything to do with interest rates. The author says that insurance is "partly" responsible, thus acknowledging that there may be other factors.

If (D) is the answer, the argument should not work without this assumption. But even if we say that interest rates are a significant factor, the argument is not affected to a high degree.

You are correct in that (D) would be a good answer in the following two cases:

1) The author stated that insurance was the only significant factor / only factor / the sole reason / etc...

2) The option (D) stated that "The difference in the interest rates... is not the sole factor in bank failures.

Be careful in distinguishing assertions that take on an extreme viewpoint vs a flexible viewpoint.

Hope that clarifies.

[Vaibhav Sinha]

Here are my 2 cents.

For me D is a tricky one. Thank god it is not worded like,

' The difference in interest rates paid to depositors by different banks, is one of important factors for depositors to decide for a certain bank.'

Because this would mean, that there are other incentives for depositor apart from bank's security to decide for the bank. Infact this statement would weaken the conclusion to a certain degree. 

But the statement here says, the difference in rates is not a significant factor in bank failures, that implicitly means different rates do not impact the depositor's decision to pick a bank based on interest rates; or it may but does not impact the conclusion. 

I initially was hooked on this option and wondered how cleverly have they worded this one. Kudos to GMAC for this. Sometimes it's critical to identify these trap answers in the question and analyze them. "Always" consider the conclusion of the argument before you take down options one by one. 

[Matt P]

Vaibhav,

Check out this one if you want to see some terribly confusing wording: (Perhaps you've already done it; it's yesterdays BeatTheGMAT Verbal question).

If there are more oak trees in Oregon than there are leaves on any one Oregon oak tree, and if every Oregon oak tree has at least one leaf, then __________. 

Which of the following most logically completes the passage? 

A. the average number of oak leaves per Oregon oak tree must be less than half the number of Oregon oak trees 
B. there are fewer leaves on at least one Oregon oak tree than half the number of those trees
C. there must be at least two oak trees in Oregon with the same number of leaves 
D. there must be at least as many Oregon oak trees with half as many leaves as the Oregon tree with the most leaves, as there are Oregon oak trees with twice as many leaves as the Oregon oak tree with the fewest leaves 
E. there must be more oak trees than any other type of tree in Oregon

[vaibhav]

OK For POE i think its D. 

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Regards,

Vaibhav

[Matt P]

Heh,

You fell into their trap of selecting the confusing one because you were too lazy to analyze it ;)

Official Answer on Google; I don't want to spoil it for anyone else who wants to try :)

[swati.pdh]

Awesome explanations...

@Matt,

I did not get the second point in below -

[Matt P]

Swati:

If the answer choice was: "The difference in the interest rates is not the sole factor in bank failures," this would be valid, because saying that insurance is a factor implies that interest rates are not the only factor.

Hope it's clear.

[Vaibhav Sinha]

This is crazy. This is hurting my head now. The reasoning is so convoluted. 

Hey I think I got it. :P

[swati.pdh]

I was solving below question and stuck on why is option A incorrect. Please have a look...


The average level of fat in the blood of people suffering from acute cases of disease W is lower than the average level for the population as a whole. Nevertheless, most doctors believe that reducing blood-fat levels is an effective way of preventing acute W.

Which one of the following, if true, does most to justify this apparently paradoxical belief?
(A) The blood level of fat for patients who have been cured of W is on average the same as that for the population at large.
(B) Several of the symptoms characteristic of acute W have been produced in laboratory animals fed large doses of a synthetic fat substitute, though acute W itself has not been produced in this way.
(C) The progression from latent to acute W can occur only when the agent that causes acute W absorbs large quantities of fat from the patient’s blood.
(D) The levels of fat in the blood of patients who have disease W respond abnormally slowly to changes in dietary intake of fat.
(E) High levels of fat in the blood are indicative of several diseases that are just as serious as W.



Is option A  a shell game type of choice? - because it says blood level of fat and not fat of blood level ??

[swati.pdh]

Hi,

Can someone please explain what is the meaning of option D? I chose D using POE but did not understand how is it an assumption.


In order to save money, some of Company X's manufacturing plants converted from oil fuel to natural gas last year, when the cost of oil was more than the cost of natural gas. Because of a sudden, unexpected shortage, however, natural gas now costs more than oil, the price of which has fallen steeply over the past year. The cost of conversion back to oil would more than negate any cost savings in fuel. So Company X's fuel costs this year will be significantly higher than they were last year.

Which of the following is an assumption on which the argument above depends?

(A) Company X does not have money set aside for the increased costs of fuel.
(B) The increase in the cost of fuel cannot be offset by reductions in other operating expenses.
(C) The price of natural gas will never again fall below that of oil.
(D) The cost of fuel needed by those of Company X's plants that converted to natural gas is not less than the cost of fuel needed by those plants still using oil.
(E) The price of oil will not experience a sudden and steep increase.