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# Burglar alarm systems can be inaccurate in two ways: they

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Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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17 Feb 2009, 22:31
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Burglar alarm systems can be inaccurate in two ways: they can fail to detect an intruder when one is present, or they can falsely report the presence of an intruder. To detect the presence of an intruder most accurately, homeowners should purchase the system that is least likely to falsely report the presence of an intruder.

If true, which of the following would most strengthen the above recommendation?

A) The police respond to automatic alerts from burglar alarms more quickly than they do to telephone calls reporting the presence of an intruder.

B) The burglar alarm system that is least likely to sound its alarm when there is no intruder present is equal in price to all other major brands of alarm systems.

C) Local police forces vary in their response rates to burglar alarm systems.

D) All burglar alarm systems have the same rate of mistaking an animal for a burglar.

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present.
[Reveal] Spoiler: OA

Last edited by Zarrolou on 25 Jul 2013, 10:39, edited 1 time in total.
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17 Feb 2009, 23:13
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A fantastic question. A real twister.
E it is.

[Alarm Defect Type 1] can fail to detect an intruder when one is present
[Alarm Defect Type 2] can falsely report the presence of an intruder

[Conclusion] homeowners should purchase the system that is least likely to falsely report the presence of an intruder. In other words , avoid [Alarm Defect Type 2].

But why [Alarm Defect Type 1] is not an consideration in the conclusion ?

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present.

In other words , [Alarm Defect Type 1] is same for all brands.

It completely makes sense just to look only avoid [Alarm Defect Type 2].

Voila !

Last edited by gmatavenue on 17 Feb 2009, 23:17, edited 1 time in total.
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18 Feb 2009, 10:00
E

Conclusion depends only on the false positive. Hence the error must be same across all alarms if False positive is the determining factor.

Thanks
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20 Oct 2012, 04:21
gmatavenue wrote:
A fantastic question. A real twister.
E it is.

[Alarm Defect Type 1] can fail to detect an intruder when one is present
[Alarm Defect Type 2] can falsely report the presence of an intruder

[Conclusion] homeowners should purchase the system that is least likely to falsely report the presence of an intruder. In other words , avoid [Alarm Defect Type 2].

But why [Alarm Defect Type 1] is not an consideration in the conclusion ?

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present.

In other words , [Alarm Defect Type 1] is same for all brands.

It completely makes sense just to look only avoid [Alarm Defect Type 2].

Voila !

Yes it's E and your method is faster than my method. Beautiful and simple.
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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01 Apr 2013, 02:30
This is the question where the assumption and the strengthen option, both are the same.

If the question would have been that what can be assumed for the argument to be true, then also the option E would have been the correct answer.
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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30 Jun 2013, 15:09
leemike114 wrote:
Hi, you shared nice piece of information and I also have some knowledge about the burglar alarms and security systems ,so I also want to share some tips for saving yourselves from burglars.
All doors that lead to the exterior of your abode should be running a heavy-duty deadbolt which has a minimum one-inch throw.Lock your windows and secure them in order that they can’t be raised ample for a person to have in from the outside.
so I would like to suggest to all my friends must install the security and burglar alarms.

brisbane alarm systems

WTF ? .................................
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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09 Jul 2013, 00:15
Burglar alarm systems can be inaccurate in two ways: they can fail to detect an intruder when one is present, or they can falsely report the presence of an intruder. To detect the presence of an intruder most accurately, homeowners should purchase the system that is least likely to falsely report the presence of an intruder.

If true, which of the following would most strengthen the above recommendation?

A) The police respond to automatic alerts from burglar alarms more quickly than they do to telephone calls reporting the presence of an intruder.

B) The burglar alarm system that is least likely to sound its alarm when there is no intruder present is equal in price to all other major brands of alarm systems.

C) Local police forces vary in their response rates to burglar alarm systems.

D) All burglar alarm systems have the same rate of mistaking an animal for a burglar.

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present.

A has a direct connect to the argument as it would result in a waste of resources
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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25 Jul 2013, 10:32
This Portion is Premise for sure:
Premise: Burglar alarm systems can be inaccurate in two ways: they can fail to detect an intruder when one is present, or they can falsely report the presence of an intruder.

This is argument or Premise-
To detect the presence of an intruder most accurately, homeowners should purchase the system that is least likely to falsely report the presence of an intruder.
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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06 Nov 2014, 08:45
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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03 Dec 2015, 13:01
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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09 Dec 2015, 12:31
Burglar alarm systems can be inaccurate in two ways: they can fail to detect an intruder when one is present, or they can falsely report the presence of an intruder. To detect the presence of an intruder most accurately, homeowners should purchase the system that is least likely to falsely report the presence of an intruder.

If true, which of the following would most strengthen the above recommendation?

A) The police respond to automatic alerts from burglar alarms more quickly than they do to telephone calls reporting the presence of an intruder.

B) The burglar alarm system that is least likely to sound its alarm when there is no intruder present is equal in price to all other major brands of alarm systems.

C) Local police forces vary in their response rates to burglar alarm systems.

D) All burglar alarm systems have the same rate of mistaking an animal for a burglar.

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present.

The answer is obviously E. Here, what is the gap? The conclusion overlooks the first way, though he points out the two. Strengthening question needs to bring a new piece of evidence that can save the author from the logical gap. The option E rules out the first way stating that no benefit on streesing on the first way. Rather, do something with the second way.
Option A is after a intruder detected.so, Offtopic.
B is actually weakening the point, since if so, the recommendation is worthless to purchase special one.
C Offtopic.
D better than other wrong answers but still, not clearly ruling out the first way, wich option E does beautifully.
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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23 Jan 2016, 13:51
So option A fixes the gap or introduces the necessary assumption to support the conclusion.
If option E is negated, then conclusion will fail.
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Re: Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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03 Feb 2016, 05:30
Burglar alarm systems can be inaccurate in two ways:

I. they can fail to detect an intruder when one is present,
or
II. they can falsely report the presence of an intruder.

To detect the presence of an intruder most accurately, homeowners should purchase the system that is least likely to falsely report the presence of an intruder.(ie., conclusion says that system which fails less in case II is preferred.)

If true, which of the following would most strengthen the above recommendation?

A) The police respond to automatic alerts from burglar alarms more quickly than they do to telephone calls reporting the presence of an intruder.............we are bothered which alarm to select not whether alarm or phone call. OFS

B) The burglar alarm system that is least likely to sound its alarm when there is no intruder present is equal in price to all other major brands of alarm systems..........price is not of concern here. OFS

C) Local police forces vary in their response rates to burglar alarm systems..............how police systems work is not needed here. OFS

D) All burglar alarm systems have the same rate of mistaking an animal for a burglar..............animal plays the spoilsport here. OFS

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present...............this indicates that ou tof the two cases above case I need not considered since it is same for all systems. This strengthen the conclusion saying that remaining case II is important here.
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Burglar alarm systems can be inaccurate in two ways: they [#permalink]

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03 Feb 2016, 05:58
Burglar alarm systems can be inaccurate in two ways: they can fail to detect an intruder when one is present, or they can falsely report the presence of an intruder. To detect the presence of an intruder most accurately, homeowners should purchase the system that is least likely to falsely report the presence of an intruder.

If true, which of the following would most strengthen the above recommendation?

A) The police respond to automatic alerts from burglar alarms more quickly than they do to telephone calls reporting the presence of an intruder.

B) The burglar alarm system that is least likely to sound its alarm when there is no intruder present is equal in price to all other major brands of alarm systems.

C) Local police forces vary in their response rates to burglar alarm systems.

D) All burglar alarm systems have the same rate of mistaking an animal for a burglar.

E) All burglar alarm systems have the same rate of failing to detect an intruder when one is present.

Quite an easy E for me

I treat it as an assumption question

Given:
Two reasons for inaccuracy in alarms-
1) fail to detect an intruder when one is present.
2) falsely report the presence of an intruder.

Conclusion:
To be more accurate- purchase the system that is least likely to falsely report the presence of an intruder.
i.e. the conclusion is based only on 'reason 2' above. It asks homeowners to minimize reason 2 and in-turn increase accuracy.

But what about reason 1?? If minimizing reason 2 alone increases the accuracy, the reason 1 should either be constant or be going down by itself among all available alarms out there(ignore the second part).

Option E says precisely this.
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Burglar alarm systems can be inaccurate in two ways: they   [#permalink] 03 Feb 2016, 05:58
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