Temurkhon wrote:
in fact, all options are not good.
Ideally, we need information saying what is percentage
of reducing capacity in people who use comp less than 20 hours.
Option E does not answer that question because "average user" can still use 20 hours
To be more specific, I would argue that "all options are not
perfect." But questions such as as these are not asking you to find the ultimate answer that plugs the logic so perfectly Aristotle himself rises from the grave and applauds you for the answer. It is easy to overthink such questions if you are looking for a perfect solution that matches all your preconceived notions. The problem simply asks, "
The response to which of the following questions would be most helpful in evaluating the reasoning presented in the survey?"
"Most helpful" doesn't mean flawless. This highlights a common trap of the GMAT which I call "
Directional Nudges" in my classes. You need to find the answer that
best does the job. Answer choice
E does exactly that. Yes, the "average user" could still "use 20 hours", but because average (by definition) aggregates ALL users (including, but not limited to, the ones discussed in the research), answer choice E provides a comparative. We just are trying to determine whether prolonged exposure to radiation from computer monitors "
diminishes" mental capacity. Since the research seems to separate out users that worked "
in excess of 20 hours per week", this means it left out of its total all those who worked below that level. On the other hand, an "average" would include those who worked
below that level. It helps us to see if the "heavily irradiated" folks are comparably different to the "slightly irradiated" folks, without knowing specifics.
It may be also worth noting for some of you studying for the GMAT that "Useful to Evaluate" questions can stop short of actually giving new data that actually proves or disproves a fact. The correct answers to such questions simply provide a future direction for research or additional possibilities that, if known, would help us make a conclusion one way or the other. Answer
E suggests the possible usefulness of knowing a comparative average percentage. Such information would allow us to conclude exactly what the question is asking: what information would help us prove (or disprove) whether "prolonged exposure" (arguably somewhere in the 20+ hours range) "diminishes" mental capacity. We don't need to know the numbers to answer the question. Hypothetically, if average mental decline over 15 years were 5%, then we would know that heavily irradiated folks seem to decline faster on average. If the same mental decline was 12%, we might suspect that monitor use had little effect. If the same average mental decline were 20%, this would hint that staring at computer screens all day might even be good for us. But don't stare at this screen for too long, or you might overthink the question.
No matter if the average turned out to be 5%, or 12%, or 20%, any of those measures would be "
helpful in evaluating the reasoning."
The answer is definitely
E.