PrepTest 149, Section 3, Question 24

What we’re looking for

Working the answers

• A

  Average damage per tornado isn't the number of tornadoes. We could have twice as many tornadoes, each causing about the same damage as before. Or we could have the same number. Keeping the average steady doesn't favor the meteorologist's claim about the actual count.

• B

  This says more tornadoes are hitting major population centers. It doesn't show that we're merely detecting more of an unchanged total. Perhaps cities have grown, or perhaps there are more tornadoes; we would need more information. If the population centers were comparable over time, an increase in tornadoes hitting them would be a reason to question the claim that the total hasn't increased.

• C
  Correct

  If total reports more than doubled while reports of large and medium tornadoes stayed about the same, the additional reports must be of smaller tornadoes. Those are the ones we'd more readily imagine earlier observers missing. This pattern fits improved detection: we're finding more of the little storms, while reports of the more conspicuous ones remain steady. It doesn't prove the actual total is unchanged, but it gives the meteorologist's explanation more support.

• D

  More deaths don't establish that the actual number of tornadoes stayed constant. Deaths can also depend on how many people are exposed and other circumstances, so we shouldn't treat them as a perfect tornado count. Either way, D provides no positive reason to attribute the additional reports to better detection.

• E

  Tornadoes could become more frequent within exactly the same geographic range. Knowing where they are most prevalent doesn't tell us how many occur there. E leaves the dispute between increased occurrence and increased detection unresolved.