A survey of alumni of the class of 1960 at Aurora University yielded puzzling results. ████ █████ ██ ████████ █████ ████████ █████ ████ ██ ███ ███████████ ████████ ████ ████ ████ ██ ███ ███ ███████ ██ ███ ██████████ █████ ██ █████
In a recent survey of Aurora University's 1960 alumni, how is it possible that half of respondents reported they had been in the top quarter of the graduating class? There are really only two possible explanations for this result: either high-ranking alumni were more likely to respond to the survey, or some of the respondents misreported their academic rank.
Which one of the following ████ █████ ███████ ███ ███ ████████ █████████████ ██████
A disproportionately large ██████ ██ ████████████ ██████ █████████ ██ ███ ███████
So for example, maybe every alumnus who had been in the top quarter of the class responded, but only a third of alumni from the bottom three-quarters responded. This explains the survey result: the alumni who chose to respond were not representative of the overall academic performance of the graduating class.
Few, if any, ███████████ ████ ████████ █████ █████ █████ █████
This just makes the result more confusing. If some respondents misremembered their class rank, that would have been one way to resolve the contradiction. But (B) only eliminates this possibility without giving us another explanation.
Not all the ██████ ███ ████ ████████ ██ ███ ███ ███████ █████████ ██ ███ ███████
(C) doesn't help to explain the confusing result, because it doesn't tell us anything about the proportion of respondents who were in the top quarter. Without knowing how many alumni from the bottom three-quarters responded to the survey, this doesn't resolve anything.
Almost all of ███ ██████ ███ █████████ ██ ████ █████████ ██ ███ ███████
(D) makes the contradiction more confusing by eliminating a possible explanation. If a disproportionate number of high-ranking alumni had responded, that would explain the result—as it does in correct answer (A). By saying that's not what happened, (D) fails to account for the contradiction.
Academic rank at ██████ ██████████ ███ █████ ██ █ ██████ ██ ██████████████ ██ ████████ ██ ███████ ███████
(E) tries to distract us from the key issue: how come half of respondents said they were in the top quarter of academic rank? Regardless of how academic rank is calculated, it's just mathematically impossible for half of alumni to be in the top quarter of the class! (E) doesn't account for that result.
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