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The National Association of Fire Fighters says that 45 percent of home

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Praetorian
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The National Association of Fire Fighters says that 45 percent of home [#permalink] New post   Updated on: 07 Apr 2019, 07:20
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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.


Source: LSAT
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D

Originally posted by Praetorian on 27 Sep 2003, 11:10.
Last edited by Bunuel on 07 Apr 2019, 07:20, edited 2 times in total.
Renamed the topic and edited the question.
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Re: The National Association of Fire Fighters says that 45 percent of home [#permalink] New post   23 Sep 2014, 14:26
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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 percent of home [#permalink] New post   13 Apr 2021, 02:45
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Praetorian 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.


Source: LSAT


OFFICIAL EXPLANATION



(A) No. Not only is this irrelevant, it is incorrect! Fully one-third of smoke detectors were installed within the last ten years, as they jumped from installations in 30 percent of homes to 45 percent.

(B) No. This is irrelevant. The conclusion concerns the probability of early detection of a house fire, not the total number of such fires.

(C) No. This is irrelevant. The conclusion only concerns the percentage of inoperable smoke detectors, not the reason the detectors are not functioning.

(D) Yes. If the proportion of smoke detectors that are inoperative is the same now as in the past, then the detection of fires would be 50 percent more likely (45 is 50 percent larger than 30). However, if the percentage of inoperable smoke detectors has increased over the last 10 years, then the chance of detecting fires would increase less than 50 percent. In fact, it is possible for so many smoke detectors to have become inoperable that there was no increase in the number of properly functioning detectors.

(E) No. The passage is discussing early detection, not safety per se.
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Re: The National Association of Fire Fighters says that 45 percent of home [#permalink] New post   27 Sep 2003, 12:41
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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 percent of home [#permalink] New post   13 Jul 2015, 10:19
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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.

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 percent of home [#permalink] 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 percent of home [#permalink] New post   12 Oct 2017, 00:47
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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 percent of home [#permalink] New post   18 Mar 2018, 05:22
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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. --Doesn't matter. They can still be faulty.

(B) The number of fires per year in homes with smoke detectors has increased. --Fires can still be detected using these detectors

(C) Not all of the smoke detectors in homes are battery operated. --These can can have other types of issues

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

(E) Unlike automatic water sprinklers, a properly functioning smoke detector cannot by itself increase fire safety in a home. --Argument is about smoke detection and not safety
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Re: The National Association of Fire Fighters says that 45 percent of home [#permalink] New post   13 Jan 2020, 17:38
I was wrong in answering the question. I opt for B.
After re-reading the the argument I could say that the argument talks about the early detection of fire and not the fire itself.
Option B talks about " The number of fires per year in homes with smoke detectors has increased. " number of fires and not the early detection. Option D - "The proportion of domestic smoke detectors that are inoperative has increased in the past ten years" on the other hand gives a reason why early detection is no more likely.
I should have gone for D.
GMATNinja, please let me know is my understanding correct.
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Re: The National Association of Fire Fighters says that 45 percent of home [#permalink] New post   28 May 2023, 02:38
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Re: The National Association of Fire Fighters says that 45 percent of home [#permalink]
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