airport

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airport

by madhur_ahuja » Wed Aug 12, 2009 9:56 pm
A certain airport security scanner designed to detect explosives in luggage will alert the scanner’s operator whenever the piece of luggage passing under the scanner contains an explosive. The scanner will erroneously alert the operator for only one percent of the pieces of luggage that contain no explosives. Thus in ninety-nine out of a hundred alerts explosives will actually be present.
The reasoning in the argument is flawed because the argument

(A) ignores the possibility of the scanner’s failing to signal an alert when the luggage does contain an explosive

(B) draws a general conclusion about reliability on the basis of a sample that is likely to be biased

(C) ignores the possibility of human error on the part of the scanner’s operator once the scanner has alerted him or her

(D) fails to acknowledge the possibility that the scanner will not be equally sensitive to all kinds of explosives

(E) substitutes one group for a different group in the statement of a percentage
Source: — Critical Reasoning |

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by ashish1986 » Wed Aug 12, 2009 10:50 pm
I Think E

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by ashish1986 » Wed Aug 12, 2009 10:50 pm
I think E

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by ankit1383 » Wed Aug 12, 2009 10:53 pm
IMO E....but not sure

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Re: airport

by mehravikas » Wed Aug 12, 2009 11:05 pm
hmmmmmm

IMO - B
madhur_ahuja wrote:A certain airport security scanner designed to detect explosives in luggage will alert the scanner’s operator whenever the piece of luggage passing under the scanner contains an explosive. The scanner will erroneously alert the operator for only one percent of the pieces of luggage that contain no explosives. Thus in ninety-nine out of a hundred alerts explosives will actually be present.
The reasoning in the argument is flawed because the argument

(A) ignores the possibility of the scanner’s failing to signal an alert when the luggage does contain an explosive

(B) draws a general conclusion about reliability on the basis of a sample that is likely to be biased

(C) ignores the possibility of human error on the part of the scanner’s operator once the scanner has alerted him or her

(D) fails to acknowledge the possibility that the scanner will not be equally sensitive to all kinds of explosives

(E) substitutes one group for a different group in the statement of a percentage

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by gauravgundal » Wed Aug 12, 2009 11:08 pm
IMO -E
Through POE

A- It argument doesn't ignores the possibility..(Incorrect)
B-The conclusion is drawn ,but it is not a general it is based of some facts .(Incorrect)
C-Outof scope nowhere it is mentioned about the operator's error. (Incorrect)
D- The argument doesn't mention about different kinds of explosive.so out of scope(Incorrect)
E-looks fine .

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by madhur_ahuja » Wed Aug 12, 2009 11:23 pm
Can anyone explain the reasoning for E ?

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by mariah » Sun Nov 15, 2009 1:55 pm

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by DeepakYakkundi » Mon Nov 16, 2009 11:07 pm
i feel that A is the answer.

The author concludes that "Thus in ninety-nine out of a hundred alerts explosives will actually be present."
i.e. in every 100 alerts 99 of them will actually be correct i.e. will be containing explosives i.e. 99%
In the evidence, he is saying - if 100 bagage will no explosives were passed, only 1 would be alerted.
However, he is assuming that if 100 baggage with explosives are passed, all would be alerted.
Thus, in every 100 alerts 99 of them will be actually be correct.

for e.g. lets say 1000 bagage were screened. 500 contained explosives, 500 didnot.
now 500 containing explosives will alert. out of other 500, only 5 will be alerted.
so 500 out of 505 alert will actually contain explosives which is 99%

In arriving at this conclusion, auther has assumed that if the bagage contains explosives, it will definately be alerted. hence answer (a) bring out this missed scenario.

TestLuv, can you pls explain whether the reasoning is correct?

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by getso » Tue Nov 17, 2009 5:31 am
Hi,

I agree with Deepak.

I go with A...

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by f2006198 » Tue Nov 17, 2009 10:00 pm
IMO E

There are four distinct sets

1.explosive-alert
2.explosive-no alert
3.no explosive-alert
4.no explosive-no alert

Clearly sets (1&2) are independent of sets (3&4). The author has given information only on (3&4) and proceeds to draw a conclusion about (1&2) which is flawed. Hence the answer.

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by heshamelaziry » Tue Nov 17, 2009 10:16 pm
There is no OA here or at thegmatclub.com, but guys who support E seem quite confident. I read all explanation for E, but don't understand what probability ahs to do with the question?

Anyone one would like to give a down to earth explanation? easy and straightforward.

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by mehravikas » Wed Nov 18, 2009 12:06 pm
We need Testluv :-)

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by heshamelaziry » Wed Nov 18, 2009 1:15 pm
I bet that A is the answer

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by mariah » Wed Nov 18, 2009 1:20 pm
that's say we have 100 baggage all without explosive!!!
and detector gave false alarm to 1 baggage...

but the argument states that 99 baggage will have explosive ...

it clearly substitutes one group for a different group!
Last edited by mariah on Wed Nov 18, 2009 1:26 pm, edited 1 time in total.