PrepTest 149

Incorrect. In talking about per-tornado damage ("average"), this answer doesn't address the total number of tornadoes. Averages "smooth out" totals, they don't address them.

Incorrect. If anything, this suggests that the number of tornadoes is increasing, as there's no reason to believe that tornadoes are more likely now to hit cities than earlier. If tornado rates are stable, we'd expect them to hit cities at the same rate as previously.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Phenomenon Ð Tornado reports are up
Explanation Ð We're getting better at spotting them, so we're probably finding a higher proportion of the same number of tornadoes

Answer Anticipation:
Another phenomenon/explanation passage! And one that we're asked to strengthen.

Generally, in dealing with this type of argument, the correct answer will either provide direct evidence for the cited explanation, or evidence against an alternative explanation. So we're best off understanding what the explanation is, and what alternative explanations there might be.

Here, the given explanation for the increased number of tornado reports is that we're spotting a larger percentage of the same number of tornadoes. Anything that supports that we're catching a higher percentage will strengthen this explanation.

While there are probably several alternatives, the one directly addressed in the stimulus is that there are more tornadoes. Any answer that undercuts this possibility will strengthen the alternative explanation from the conclusion.

Answer Explanation:
Since reports are up, but reports on large and medium-sized tornadoes are stable, this answer establishes that the reports on small tornadoes are up. It also establishes some stability in the total number of tornadoes, in that the number of reported large and medium tornadoes (more likely to be noticed, those) is stable. Since these smaller tornadoes are less likely to be noticed than larger ones, the fact that reports on them are up suggests that we are finding a higher proportion of tornadoes, strengthening the argument.

Key Takeaway:
Phenomenon/explanation arguments usually have answers that address alternative explanations. When they don't, the answers usually directly address the explanation from the conclusion.

Incorrect. Fatalities aren't tied to the number of tornadoes. One explanation for more tornado-related fatalities is more tornadoes (which would weaken the argument), but another is that the number of tornadoes has stayed stable but the intensity of each has increased. Since this answer doesn't necessarily speak to the conclusion (or it does, but not with enough information to determine which way it cuts), we can eliminate it.

Incorrect. This answer can feel as if it strengthens the argument by creating a similarity between the present and past, thus leading to the conclusion that the number of tornadoes probably hasn't changed. However, those two ideas aren't inherently linked—there can be many more tornadoes in the same range.