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Parallel Flaw—#%. The correct answer choice is (C)
The stimulus argues that since the average price of groceries will rise next month, the price of two
specifi c goods—butter and eggs—will rise next month. This is a classic error of division where a
characteristic of the whole is presumed to apply to all of its parts. Specifi cally, in this problem the
conclusion is unwarranted because the increase in the average price of groceries could be attributed
to many items other than butter or eggs. In fact, the price of butter and eggs could have decreased
because the overall qualities of a group are not necessarily shared by each part of the group.
Note that the correct answer must contain a fl aw similar to the one in the stimulus. Any answer
choice featuring valid reasoning or a different type of fl aw should be eliminated.
Answer choice (A): This answer is incorrect on two counts. First, the choice projects a past trend
into the future, whereas the argument in the stimulus involves the future but not the past. Second,
this choice does not use a general average and apply it to specifi c items. Instead, a single item is
addressed throughout the answer.
Answer choice (B): This choice states that only two outcomes are possible, and then concludes that a
since one of the options is unlikely to occur that the other option must occur. Although the reasoning
is fl awed, it is not analogous to that found in the stimulus.
Answer choice (C): This is the correct answer choice. The answer addresses a characteristic
(amount of time spent watching television) of a general group (people younger than 20) and indicates
that the average characteristic is increasing. The answer then concludes that the characteristic of
a part (fourth graders) of the general group must also have risen. Similar to the argument in the
stimulus, this argument ignores the fact that an average increase does not mean that every part of the
group has increased.
Answer choice (D): This choice contains valid conditional reasoning. If the price of ice cream
rises whenever the price of sugar rises, and next month the price of sugar is expected to rise, then it
follows that next month the price of ice cream is expected to rise. Conditionally speaking, one of the
premises contains the following relationship:
Price of sugar rises Price of ice cream rises
Another premise indicates that next month the suffi cient condition is expected to occur, and thus one
can conclude that next month the necessary condition is likely to occur.
Note that although this argument contains a part to whole relationship, there is not the same fl awed
use of an average and its component parts.
Answer choice (E): This choice also contains conditional reasoning. The fi rst sentence contains both
a conditional relationship and the statement that the suffi cient condition will occur over the next
Conditional Relationship: Population 20-30 declines Real estate prices fall
Suffi cient condition met: Population 20-30 declines over next decade
Consequently, we can conclude that the necessary condition will also occur over that period, and that
real estate prices fall over the next decade.
Note also that there is no part to whole relationship within this answer, so this answer is incorrect on
that count as well.