Bunuel wrote:
Which of the following most logically completes the argument?
The city is threatened by an impending tropical storm, which is expected to raise the water outside the city to levels approaching the height of the protective barrier along the coast. Three teams of engineers and oceanographers have independently predicted the maximum water level will reach 89%, 83%, and 88% of the height of the protective barrier. The city is sufficiently safe, provided that _______________.
A. we take additional, sufficient steps to safeguard the city
B. the uncertainty of the predictions is sufficiently small relative to the difference between the predicted water level and the barrier's height
C. no additional independent prediction yields a value of 95% or higher
D. the three teams of engineers and oceanographers have based their predictions on similar assumptions
E. the three teams of engineers and oceanographers have based their predictions on dissimilar assumptions
OFFICIAL EXPLANATION:
Reading the question: since we must make a logical continuation, we try to predict the answer. The only prediction that springs to mind is a simplistic one: "The city is sufficiently safe, provided that their predictions are correct." That is our predicted answer about their predictions about the storm. Even a simple or obvious prediction can be used as a basic relevance filter.
Applying the filter: choices (B) through (E) are all relevant to the basic question of the correctness of the prediction. One is objectively best, while the rest are objectively not best. (B) seems best, so we can attempt to establish logical proof for (B).
Logical proof: we can confirm answer choice (B) by analysis by cases. Imagine that each team gave a certainty of plus or minus 50% the height of the wall. In that case, the city is not sufficiently safe. On the other hand, if the certainty is plus or minus 1%, the city is safe. Choice (B) must be right. Similar analysis of choices (C), (D), and (E) shows that they are not material to the argument in such a way.
The correct answer is (B).
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