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16 Sep 2014, 02:29
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City air contains more carbon monoxide than does rural air, and plants in cities typically grow more slowly than do plants in rural areas. In an experiment to see how much of the difference in growth is due to carbon monoxide, classes in a city and a rural school grew plants in greenhouses at their schools and filtered the greenhouse air to eliminate carbon monoxide. Plants in the city greenhouse grew more slowly than those in the rural greenhouse.
Which of the following, if true, would it be most important to take into account in evaluating the result?
A. The city school was located in a part of the city in which levels of carbon monoxide in the air were usually far lower than is typical for city areas.
B. At both schools, the plants in the greenhouses grew much more quickly than did plants planted outdoors in plots near the greenhouses.
C. The city class conducting the experiment was larger than the rural class conducting the experiment.
D. Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside.
E. Because of the higher levels of carbon monoxide in the air at the city school, the air filters for the city school’s greenhouse were changed more frequently than were those at the rural school.
Which of the following, if true, would it be most important to take into account in evaluating the result?
A. The city school was located in a part of the city in which levels of carbon monoxide in the air were usually far lower than is typical for city areas.
B. At both schools, the plants in the greenhouses grew much more quickly than did plants planted outdoors in plots near the greenhouses.
C. The city class conducting the experiment was larger than the rural class conducting the experiment.
D. Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside.
E. Because of the higher levels of carbon monoxide in the air at the city school, the air filters for the city school’s greenhouse were changed more frequently than were those at the rural school.
16 Sep 2014, 02:29
Kudos
Bookmarks
Official Solution:
City air contains more carbon monoxide than does rural air, and plants in cities typically grow more slowly than do plants in rural areas. In an experiment to see how much of the difference in growth is due to carbon monoxide, classes in a city and a rural school grew plants in greenhouses at their schools and filtered the greenhouse air to eliminate carbon monoxide. Plants in the city greenhouse grew more slowly than those in the rural greenhouse.
Which of the following, if true, would it be most important to take into account in evaluating the result?
A. The city school was located in a part of the city in which levels of carbon monoxide in the air were usually far lower than is typical for city areas.
B. At both schools, the plants in the greenhouses grew much more quickly than did plants planted outdoors in plots near the greenhouses.
C. The city class conducting the experiment was larger than the rural class conducting the experiment.
D. Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside.
E. Because of the higher levels of carbon monoxide in the air at the city school, the air filters for the city school’s greenhouse were changed more frequently than were those at the rural school.
General Approach
In critical reasoning questions like these, the goal is usually to identify the underlying assumption or factor that wasn't considered in the initial experiment or argument. The first step is to understand the context and the argument presented: in this case, even though air was filtered to eliminate carbon monoxide, plants in the city greenhouse still grew more slowly than those in the rural greenhouse.
Correct Answer Explanation
Answer choice D provides a factor that wasn’t initially considered: the presence of grime on the surfaces of the greenhouses. In cities, heavy vehicular traffic constantly deposits grime on greenhouse windows which can reduce the amount of light that reaches the plants inside. Plants need light for photosynthesis, so a reduction in light could cause slower growth. This means that even though carbon monoxide was removed from the air, there was still a significant difference between the environments in the city and rural greenhouses that could affect plant growth.
Incorrect Answer Explanations
A) Even if the city school is located in an area with lower carbon monoxide levels, this information is irrelevant because both greenhouses had their air filtered to eliminate carbon monoxide, thus neutralising any prior differences.
B) The fact that plants in both greenhouses grew quicker than plants outside doesn’t help explain the difference in growth rate between the city and rural greenhouses, as this is a similarity between the two scenarios, not a difference.
C) The size of the classes conducting the experiment doesn’t affect the growth of the plants in the greenhouse, making this information irrelevant.
E) This answer choice indicates that the city greenhouse’s air filters were changed more frequently due to higher carbon monoxide levels. However, since both greenhouses had their air filtered to eliminate carbon monoxide, the frequency of filter changes shouldn’t affect the growth rate of the plants and thus doesn’t explain the difference in growth rate between the city and rural greenhouses.
Answer: D
City air contains more carbon monoxide than does rural air, and plants in cities typically grow more slowly than do plants in rural areas. In an experiment to see how much of the difference in growth is due to carbon monoxide, classes in a city and a rural school grew plants in greenhouses at their schools and filtered the greenhouse air to eliminate carbon monoxide. Plants in the city greenhouse grew more slowly than those in the rural greenhouse.
Which of the following, if true, would it be most important to take into account in evaluating the result?
A. The city school was located in a part of the city in which levels of carbon monoxide in the air were usually far lower than is typical for city areas.
B. At both schools, the plants in the greenhouses grew much more quickly than did plants planted outdoors in plots near the greenhouses.
C. The city class conducting the experiment was larger than the rural class conducting the experiment.
D. Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside.
E. Because of the higher levels of carbon monoxide in the air at the city school, the air filters for the city school’s greenhouse were changed more frequently than were those at the rural school.
General Approach
In critical reasoning questions like these, the goal is usually to identify the underlying assumption or factor that wasn't considered in the initial experiment or argument. The first step is to understand the context and the argument presented: in this case, even though air was filtered to eliminate carbon monoxide, plants in the city greenhouse still grew more slowly than those in the rural greenhouse.
Correct Answer Explanation
Answer choice D provides a factor that wasn’t initially considered: the presence of grime on the surfaces of the greenhouses. In cities, heavy vehicular traffic constantly deposits grime on greenhouse windows which can reduce the amount of light that reaches the plants inside. Plants need light for photosynthesis, so a reduction in light could cause slower growth. This means that even though carbon monoxide was removed from the air, there was still a significant difference between the environments in the city and rural greenhouses that could affect plant growth.
Incorrect Answer Explanations
A) Even if the city school is located in an area with lower carbon monoxide levels, this information is irrelevant because both greenhouses had their air filtered to eliminate carbon monoxide, thus neutralising any prior differences.
B) The fact that plants in both greenhouses grew quicker than plants outside doesn’t help explain the difference in growth rate between the city and rural greenhouses, as this is a similarity between the two scenarios, not a difference.
C) The size of the classes conducting the experiment doesn’t affect the growth of the plants in the greenhouse, making this information irrelevant.
E) This answer choice indicates that the city greenhouse’s air filters were changed more frequently due to higher carbon monoxide levels. However, since both greenhouses had their air filtered to eliminate carbon monoxide, the frequency of filter changes shouldn’t affect the growth rate of the plants and thus doesn’t explain the difference in growth rate between the city and rural greenhouses.
Answer: D
