LR Drill Set 13, Question 7
Twenty percent of the population of Springhill has(50 more words not shown)
The argument is faulty because(5 more words not shown)
- Asome of the(16 more words not shown)
- Bsome of the(16 more words not shown)
- Csome of the(20 more words not shown)
- Dnone of the(20 more words not shown)
- Enone of the(19 more words not shown)
Reading the argument
What if the same people visited both countries?
Imagine Springhill has 100 residents. Twenty went to Italy and thirty went to France. If all twenty Italy visitors are also among the thirty France visitors, we've identified only thirty different travelers—not fifty.
Adding 20 and 30 counts those twenty people twice. We need to know how much the groups overlap before using the sum as a count of distinct people. At the other extreme, if nobody visited both, the two groups would contain fifty different residents.
What we’re looking for
The immediate flaw in this addition is clear: the totals don't establish fifty different visitors. For the flaw question, look for the possibility of people appearing in both groups.
Working the answers
- A
Some residents visiting neither country is compatible with the author's conclusion. The author says half the population visited Europe, not everyone. Identifying nonvisitors doesn't address whether the twenty-percent and thirty-percent groups overlap.
- BCorrect
Some residents visited both Italy and France. Those people appear in both percentages, so simply adding the two percentages would count them twice.
For example, if ten of our hundred residents visited both, the two groups would include forty different people: twenty plus thirty minus the ten counted twice. The numbers therefore don't establish the claimed half of the population. Other European travel could add people, but that would require information the argument doesn't provide.
- C
Some people visiting just one of the countries doesn't settle the overlap among everyone else. The original addition would work for the Italy-or-France total if the entire two groups were separate, but C only says some visitors went to one country and not the other. That isn't the neglected possibility that makes the addition misleading.
- D
If nobody visited any other European country, that would help connect the Italy-or-France count to the Europe count. It still wouldn't tell us whether the two groups overlap. D removes a possible complication rather than identifying the overlap problem in the reasoning.
- E
Repeat visits to the same country don't change the percentage of people who have been there at least once. A resident going to France five times is still one resident in the thirty-percent group. The double-counting problem concerns appearing in both country groups, not taking multiple trips to one country.
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