Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 22 May 2017, 23:47

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# A certain airport security scanner designed to detect

Author Message
Director
Joined: 20 Apr 2005
Posts: 584
Followers: 2

Kudos [?]: 226 [0], given: 0

A certain airport security scanner designed to detect [#permalink]

### Show Tags

20 Jun 2005, 11:32
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

24. A certain airport security scanner designed to detect explosives in luggage will alert the scannerâ€™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 scannerâ€™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 scannerâ€™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
VP
Joined: 30 Sep 2004
Posts: 1482
Location: Germany
Followers: 6

Kudos [?]: 347 [0], given: 0

### Show Tags

20 Jun 2005, 12:54
A)...
_________________

If your mind can conceive it and your heart can believe it, have faith that you can achieve it.

SVP
Joined: 16 Oct 2003
Posts: 1805
Followers: 5

Kudos [?]: 154 [0], given: 0

### Show Tags

20 Jun 2005, 13:17
A is my answer as well.
Intern
Joined: 22 Jun 2005
Posts: 38
Followers: 0

Kudos [?]: 3 [0], given: 0

### Show Tags

29 Jun 2005, 07:25
i would go in for D.
Senior Manager
Joined: 06 Apr 2005
Posts: 349
Location: USA
Followers: 2

Kudos [?]: 112 [0], given: 1

### Show Tags

29 Jun 2005, 08:16
Wow.. I am gonna digress from the crowd for a change. My answer is E. Here is why

Lets assume for argument's sake that the machine erroneouly alerted the scanner for explosives when there were none present in 10 out of a thousand cases.. or 1% of all bags. if you were to randomly choose a 100 cases, then it is quite possible that three of those 10 cases (where the machine tagged the baggage by mistake) ended up in the set of 100. Thus the conclusion drawn is wrong, and only E points the flaw in the conclusion.
Senior Manager
Joined: 30 May 2005
Posts: 373
Followers: 1

Kudos [?]: 11 [0], given: 0

### Show Tags

29 Jun 2005, 08:29
E is my choice. Consider the possibility that a 100,000 bags pass thru the scanner with NONE of them having explosives. The scanner will ring 100 times and be 100% wrong.

A is wrong because it directly contradicts an assertion in the statement.
Senior Manager
Joined: 04 May 2005
Posts: 279
Location: CA, USA
Followers: 1

Kudos [?]: 56 [0], given: 0

### Show Tags

29 Jun 2005, 21:07
E for me

'99% being the probablity' does not translate into 99 out of 100.

In fact, 100 is too small a sample pool for the probablity calculation.

For example, I bought 100 lottery tickets and got one big win, that does not
mean my chance of winning big is 1%
Director
Joined: 18 Feb 2005
Posts: 670
Followers: 1

Kudos [?]: 6 [0], given: 0

### Show Tags

29 Jun 2005, 22:03
Agree with E
Senior Manager
Joined: 03 Nov 2004
Posts: 488
Followers: 2

Kudos [?]: 12 [0], given: 0

### Show Tags

03 Jul 2005, 21:19
E baby, its gotta be E // 0.01 -> error with NO explosive , but this doesnt mean that the rest 0.99 will have one, exactly as answer choice E.
03 Jul 2005, 21:19
Similar topics Replies Last post
Similar
Topics:
Authors writing detective stories frequently include a 2 20 Jun 2011, 19:33
A certain airport security scanner designed to detect 10 02 Jul 2010, 10:27
1 Mystery stories often feature a brilliant detective and the 10 27 Oct 2008, 08:38
1 Mystery stories often feature a brilliant detective and the 8 07 May 2008, 18:21
Display posts from previous: Sort by