PrepTest 106, Section 2, Question 3
Opponents of allowing triple-trailer trucks to use the(67 more words not shown)
Which one of the following,(7 more words not shown)
- AIt takes two(12 more words not shown)
- BHighways in the(22 more words not shown)
- COpponents of the(15 more words not shown)
- DIn areas where(12 more words not shown)
- EFor triple-trailers the(19 more words not shown)
Reading the argument
Why are we comparing western highways with the country as a whole? A lower fatality rate might tell us something about where these trucks are driven rather than how safe the trucks themselves are.
Maybe the western routes have less traffic or easier driving conditions. If triple-trailers mainly use those roads while the comparison vehicles also use crowded, difficult roads elsewhere, the vehicles haven't been compared under similar conditions. Triple-trailers could have the lower measured rate without being safer when put on the same roads as the other vehicles.
The statistic is per mile, so the issue isn't simply that fewer miles might have been driven. It's what happens on those miles. A quiet, easy mile and a crowded, difficult mile don't necessarily pose the same risk.
What we’re looking for
To weaken the argument, I'd look for evidence that western roads are safer. That would give us another explanation for the lower fatality rate and undermine the jump from a regional result to a conclusion about the vehicles generally.
Working the answers
- A
Carrying more weight per vehicle may matter when planning how to move a shipment, but it doesn't show whether a triple-trailer is safer than other commercial vehicles. We would need more information about the risks of the competing ways to carry that load. Capacity alone doesn't expose the problem in this comparison of fatality rates per mile.
- BCorrect
The western roads are much less heavily traveled and consequently much safer. That gives us exactly the difference in driving conditions we were worried about.
Suppose a less safe vehicle operates on very safe roads, while a safer vehicle operates on more dangerous roads. The first could still have a lower observed fatality rate. B doesn't prove triple-trailers are dangerous, and it doesn't need to. It shows why their western record is not a fair basis for declaring them safer than vehicles measured across the national system.
- C
The opponents' earlier opposition doesn't establish whether they were wrong then or are wrong now. Nor does the fact that twin-trailers became common establish that they are safe. We need evidence bearing on the present safety comparison, not merely a history of the opponents objecting to another vehicle.
- D
A special license alone tells us neither what extra training is required nor how triple-trailer drivers compare with other commercial drivers. If the requirement selected exceptionally capable drivers, that might help explain their record, but the answer doesn't provide that information. B directly establishes safer driving conditions; D leaves us to invent the relevant difference.
- E
The triple-trailer rate could have risen and still be below the rate for other vehicles. For example, an increase from a very low rate to a somewhat higher one would not settle the comparison. E compares triple-trailers across years, while the conclusion compares triple-trailers with other commercial vehicles.
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