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The National Association of Fire Fighters says that 45

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The National Association of Fire Fighters says that 45 [#permalink]

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13. The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.

(B) The number of fires per year in homes with smoke detectors has increased.

(C) Not all of the smoke detectors in homes are battery operated.

(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.

(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home.

Source: LSAT
[Reveal] Spoiler: OA

Last edited by broall on 20 Sep 2017, 02:44, edited 1 time in total.
Reformatted question

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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 27 Sep 2003, 12:41
I vote for D. If the proportion of domestic smoke detectors that are inoperative had decreased in the past ten years, then this would have made early detection of house fires more likely.

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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 28 Sep 2003, 11:31
The negation rule really works.

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Lsat:The National Association of Fire Fighters says that [#permalink]

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The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.

(B) The number of fires per year in homes with smoke detectors has increased.

(C) Not all of the smoke detectors in homes are battery operated.

(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.

(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home
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Re: Lsat:The National Association of Fire Fighters says that [#permalink]

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New post 23 Sep 2014, 14:26
lavanyak92 wrote:
The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.


The question tells us that 45% of homes now have smoke detectors, but, more than half of those don't work. So less than 22.5% have working smoke detectors. If the same proportion of smoke detectors didn't work ten years ago, then less than 15% of homes would have had working detectors then, and more homes would have working detectors now than before. The conclusion of the argument, that smoke detection is not better now than before, can only be true if (a lot) more detectors are inoperative now than ten years ago, which is what D says.
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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 13 Jul 2015, 01:09
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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 13 Jul 2015, 10:19
The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

The conclusion is that smoke detectors are still not effective despite the increase in their prevalence because many of them don't function (due to lack of batteries or other issue).

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.
not relevant
(B) The number of fires per year in homes with smoke detectors has increased.
not relevant
(C) Not all of the smoke detectors in homes are battery operated.
There are also other reasons that they are inoperative.
(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.
If just as many detectors were inoperative in the past, their current inefficacy can't be attributed to malfunction.
(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home. out of scope
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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 24 Aug 2015, 07:35
I made a silly mistake to not think the stimulus properly and opted the choice E. Choice E is completely out of scope.
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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 07 Jul 2016, 14:37
I got stuck between option B and D.
Option b says Number of fires have increased in houses thereby supporting that fires are no more likely to be detected with smoke detectors which mostly are inoperative or without battery
Option D also passes negation test.
Can you help with getting more clarity

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Re: Lsat:The National Association of Fire Fighters says that [#permalink]

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New post 10 Sep 2016, 13:22
lavanyak92 wrote:
The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.

(B) The number of fires per year in homes with smoke detectors has increased.

(C) Not all of the smoke detectors in homes are battery operated.

(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.

(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home


negate D
if such is true, the argument is not valid.
i'll go with D.

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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 09 Oct 2017, 09:42
OptimusPrepJanielle wrote:
The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

The conclusion is that smoke detectors are still not effective despite the increase in their prevalence because many of them don't function (due to lack of batteries or other issue).

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.
not relevant
(B) The number of fires per year in homes with smoke detectors has increased.
not relevant
(C) Not all of the smoke detectors in homes are battery operated.
There are also other reasons that they are inoperative.
(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.
If just as many detectors were inoperative in the past, their current inefficacy can't be attributed to malfunction.
(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home. out of scope



hi

I was stuck between B and D, and perhaps still now

The conclusion - smoke detectors are not effective - can also be drawn if assumed choice B

please let me resolve the issue

thanks in advance

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Re: The National Association of Fire Fighters says that 45 [#permalink]

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gmatcracker2017 wrote:
OptimusPrepJanielle wrote:
The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

The conclusion is that smoke detectors are still not effective despite the increase in their prevalence because many of them don't function (due to lack of batteries or other issue).

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.
not relevant
(B) The number of fires per year in homes with smoke detectors has increased.
not relevant
(C) Not all of the smoke detectors in homes are battery operated.
There are also other reasons that they are inoperative.
(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.
If just as many detectors were inoperative in the past, their current inefficacy can't be attributed to malfunction.
(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home. out of scope



hi

I was stuck between B and D, and perhaps still now

The conclusion - smoke detectors are not effective - can also be drawn if assumed choice B

please let me resolve the issue

thanks in advance


Since we are already given a reason for "early detection of house fires no more likely", an increase in the number of fires per year in homes with smoke detectors cannot be a correct assumption. A correct assumption to the conclusion will be on the lines of the increase in the PROPORTION/PERCENTAGE of homes with smoke detectors.

Only if the PERCENTAGE of malfunctioning smoke detectors has increased, we will nullify the advantage of increase in PERCENTAGE of homes with smoke detectors and hence arrive at the conclusion that "early detection of house fires no more likely".

Also note that a common misconception is that an increase/decrease in PERCENTAGE automatically leads to increasing/decreasing numbers. Option B talks about numbers and Option D talks about percentage. The question only gives us information about PERCENTAGES.

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Re: The National Association of Fire Fighters says that 45 [#permalink]

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New post 12 Oct 2017, 10:28
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fmik7894 wrote:
gmatcracker2017 wrote:
OptimusPrepJanielle wrote:
The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. This makes early detection of house fires no more likely, however, because over half of the domestic smoke detectors are either without batteries or else inoperative for some other reason.

The conclusion is that smoke detectors are still not effective despite the increase in their prevalence because many of them don't function (due to lack of batteries or other issue).

In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?

(A) Fifteen percent of domestic smoke detectors were installed less than 10 years ago.
not relevant
(B) The number of fires per year in homes with smoke detectors has increased.
not relevant
(C) Not all of the smoke detectors in homes are battery operated.
There are also other reasons that they are inoperative.
(D) The proportion of domestic smoke detectors that are inoperative has increased in the past ten years.
If just as many detectors were inoperative in the past, their current inefficacy can't be attributed to malfunction.
(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home. out of scope



hi

I was stuck between B and D, and perhaps still now

The conclusion - smoke detectors are not effective - can also be drawn if assumed choice B

please let me resolve the issue

thanks in advance


Since we are already given a reason for "early detection of house fires no more likely", an increase in the number of fires per year in homes with smoke detectors cannot be a correct assumption. A correct assumption to the conclusion will be on the lines of the increase in the PROPORTION/PERCENTAGE of homes with smoke detectors.

Only if the PERCENTAGE of malfunctioning smoke detectors has increased, we will nullify the advantage of increase in PERCENTAGE of homes with smoke detectors and hence arrive at the conclusion that "early detection of house fires no more likely".

Also note that a common misconception is that an increase/decrease in PERCENTAGE automatically leads to increasing/decreasing numbers. Option B talks about numbers and Option D talks about percentage. The question only gives us information about PERCENTAGES.


thank you

the argument is talking about percentages but choice B comes up with hard numbers, that's the point ...
easy one actually
thanks to you again, man

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Re: The National Association of Fire Fighters says that 45   [#permalink] 12 Oct 2017, 10:28
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