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22 Mar 2021, 02:00
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
85%
(hard)
Question Stats:
56% (02:34) correct
44%
(02:44)
wrong
based on 703
sessions
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Not Attempted Yet
County building inspectors report that almost fifty percent of the homes they inspect are equipped with gauges that monitor carbon monoxide levels. Fifteen years ago, only twenty-five percent of inspected homes were equipped with these gauges. However, even though more homes are now monitored for poisonous carbon monoxide fumes, the total number of homes with confirmed dangerous fume levels is no higher now than it was fifteen years ago because a large proportion of gauges produce false readings.
Which one of the following assumptions must be made in order for the author to be correct in drawing the conclusion stated in the passage?
(A) Thirty percent of the residential carbon monoxide gauges have been installed within the last fifteen years.
(B) The number of confirmed dangerous fume readings per year in homes with carbon monoxide gauges has increased in recent years.
(C) Not all carbon monoxide gauges report false carbon monoxide fume levels.
(D) The percentage of malfunctioning carbon monoxide gauges has increased in the last fifteen years.
(E) Properly functioning gauges do not, in themselves, decrease the risk that dangerous carbon monoxide fumes will enter people’s homes.
Which one of the following assumptions must be made in order for the author to be correct in drawing the conclusion stated in the passage?
(A) Thirty percent of the residential carbon monoxide gauges have been installed within the last fifteen years.
(B) The number of confirmed dangerous fume readings per year in homes with carbon monoxide gauges has increased in recent years.
(C) Not all carbon monoxide gauges report false carbon monoxide fume levels.
(D) The percentage of malfunctioning carbon monoxide gauges has increased in the last fifteen years.
(E) Properly functioning gauges do not, in themselves, decrease the risk that dangerous carbon monoxide fumes will enter people’s homes.
29 Mar 2021, 02:15
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Official Explanation
If the percentage of malfunctioning carbon monoxide gauges is the same now as it was fifteen years ago, then the number of homes with confirmed dangerous fume levels would be twice as high today as it was then because there are twice as many gauges in homes now (50% is twice as high as 25%). But if the percentage of defective gauges has increased within the last fifteen years, then the number of confirmed dangerous readings would decrease, perhaps even to the numbers experienced fifteen years ago. But this would occur only if the proportion of defective gauges increased dramatically within the last fifteen years. Thus, selection (D) is the correct answer.
Since the assumption is based on the proportion of gauges that accurately read fume levels, selection (A) is irrelevant. Selection (B) is inconsistent with the author’s conclusion. Selection (C) does not provide us with any information as to how many gauges are flawed. This statement would be true if even one gauge works properly. Selection (E) might be true, but it has no bearing on the author’s conclusion and the assumptions upon which it is based.
General Discussion
22 Mar 2021, 06:59
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County building inspectors report that almost fifty percent of the homes they inspect are equipped with gauges that monitor carbon monoxide levels. Fifteen years ago, only twenty-five percent of inspected homes were equipped with these gauges. However, even though more homes are now monitored for poisonous carbon monoxide fumes, the total number of homes with confirmed dangerous fume levels is no higher now than it was fifteen years ago because a large proportion of gauges produce false readings.
Which one of the following assumptions must be made in order for the author to be correct in drawing the conclusion stated in the passage?
Let there be 1000 homes inspected now. Then 500 homes have gauges installed i.e. monitored. Let, 15 years ago, total inspected homes were 400 i.e. 100 had installed gauges, thus monitored. So, it can be possible that all those 100 homes that had gauges installed reported no false readings i.e. 100 homes with fumes. Now, again after 15 years later 100 homes have fumes either those same homes or some of them('100 - some' giving false readings) with some new ones have properly functioning gauges. This means that now 400 homes have gauges that give false readings.
(A) Thirty percent of the residential carbon monoxide gauges have been installed within the last fifteen years. - INCORRECT. First, it gives too sure a figure(30%). Second, more than 30% are installed in last fifteen years. Less than 30% is also possible if we take figures accordingly.
(B) The number of confirmed dangerous fume readings per year in homes with carbon monoxide gauges has increased in recent years. - INCORRECT. It should have been decreased since in the figures taken by us, it is possible that this number has remained same or may have decreased. Most importantly, per year figures we are not sure about.
(C) Not all carbon monoxide gauges report false carbon monoxide fume levels. - INCORRECT. It can be true that there are gauges that don't give proper readings but it is also possible that all give false readings. Example: 15 years earlier out of 100, all 100 reported false readings i.e. '0' houses with fumes(on paper). Then, it is possible that '0' have fumes now without invalidating the fact that 'a large proportion of gauges produce false readings'.
(D) The percentage of malfunctioning carbon monoxide gauges has increased in the last fifteen years. CORRECT - If only '1' house has fumes, then certainly the statement is true - 99%(99/100) were malfunctioning and now the percentage is 99.8%.(499/500). If out of 100 only 1 was malfunctioning 15 years ago (1% malfunctioning) i.e. 99 were functioning properly, then now the malfunctioning percentage is >80%(401/500).
(E) Properly functioning gauges do not, in themselves, decrease the risk that dangerous carbon monoxide fumes will enter people’s homes. - INCORRECT. Decreasing the risk is not discussed in the passage. Irrelevant.
IMO Answer D.
Which one of the following assumptions must be made in order for the author to be correct in drawing the conclusion stated in the passage?
Let there be 1000 homes inspected now. Then 500 homes have gauges installed i.e. monitored. Let, 15 years ago, total inspected homes were 400 i.e. 100 had installed gauges, thus monitored. So, it can be possible that all those 100 homes that had gauges installed reported no false readings i.e. 100 homes with fumes. Now, again after 15 years later 100 homes have fumes either those same homes or some of them('100 - some' giving false readings) with some new ones have properly functioning gauges. This means that now 400 homes have gauges that give false readings.
(A) Thirty percent of the residential carbon monoxide gauges have been installed within the last fifteen years. - INCORRECT. First, it gives too sure a figure(30%). Second, more than 30% are installed in last fifteen years. Less than 30% is also possible if we take figures accordingly.
(B) The number of confirmed dangerous fume readings per year in homes with carbon monoxide gauges has increased in recent years. - INCORRECT. It should have been decreased since in the figures taken by us, it is possible that this number has remained same or may have decreased. Most importantly, per year figures we are not sure about.
(C) Not all carbon monoxide gauges report false carbon monoxide fume levels. - INCORRECT. It can be true that there are gauges that don't give proper readings but it is also possible that all give false readings. Example: 15 years earlier out of 100, all 100 reported false readings i.e. '0' houses with fumes(on paper). Then, it is possible that '0' have fumes now without invalidating the fact that 'a large proportion of gauges produce false readings'.
(D) The percentage of malfunctioning carbon monoxide gauges has increased in the last fifteen years. CORRECT - If only '1' house has fumes, then certainly the statement is true - 99%(99/100) were malfunctioning and now the percentage is 99.8%.(499/500). If out of 100 only 1 was malfunctioning 15 years ago (1% malfunctioning) i.e. 99 were functioning properly, then now the malfunctioning percentage is >80%(401/500).
(E) Properly functioning gauges do not, in themselves, decrease the risk that dangerous carbon monoxide fumes will enter people’s homes. - INCORRECT. Decreasing the risk is not discussed in the passage. Irrelevant.
IMO Answer D.
