PrepTest 106, Section 3, Question 19
On a certain day, nine scheduled flights on(53 more words not shown)
The argument depends on which(5 more words not shown)
- AMore than one(10 more words not shown)
- BSwift Airlines has(11 more words not shown)
- CEach of the(13 more words not shown)
- DSwift Airlines had(14 more words not shown)
- EAll of the(12 more words not shown)
Reading the argument
Nine cancellations could have many explanations: bad weather, too few pilots, or mechanical trouble. I don't yet know how unusual that number is for this airline.
The author says mechanical trouble ordinarily explains cancellations, but problems with more than one or two planes in a day are unlikely. On a first reading, I can see why the author suspects something else. The conclusion only says “probably,” so it leaves room for an unusual day with more mechanical problems than expected.
I'd still wonder about an event that could affect several planes at once. Perhaps a newly discovered problem with a part grounded several aircraft. That is only a possibility, and it doesn't automatically defeat a conclusion about what probably happened. But it reminds us not to treat an unlikely event as impossible.
What we’re looking for
The necessary-assumption question asks what the argument needs for its reasoning to work. I don't have a precise answer yet. I'll check which choice the comparison relies on, rather than choose a fact merely because it sounds like a plausible explanation for the cancellations.
Working the answers
- ACorrect
Here's the distinction I missed on the first reading: nine flights don't necessarily mean nine airplanes. One plane might make several trips in a day. Imagine two planes scheduled to travel back and forth between the same cities, covering all nine flights between them. If those two planes broke down, every flight could be canceled.
That situation would fit the author's limit of one or two planes with mechanical trouble without requiring another cause. The argument therefore needs more than one or two airplanes to have been scheduled for the canceled flights. Otherwise, comparing nine cancellations with one or two troubled planes doesn't support the conclusion as intended.
- B
How Swift compares with other airlines doesn't settle what caused its nine cancellations. Swift could be better or worse than its competitors and still have the pattern of mechanical trouble the argument describes. No industry ranking is required.
- C
Long flights aren't needed for this inference. The canceled trips could have been short hops. The argument compares a number of flights with the expected number of planes having problems, not the flights' lengths.
- D
This day doesn't have to be unprecedented. Swift might have canceled many flights during an earlier storm, for example. The argument concerns the likely causes on this particular day; it doesn't need a claim that no previous day had more than two cancellations.
- E
The planes could be based at different airports. The author gives us no reason the inference would depend on a shared home airport. A location requirement doesn't address the missing connection between how many flights were canceled and how many planes they used.
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