LR Drill Set 7, Question 4
Cruise ship captain: Whatever the source of the(60 more words not shown)
The conclusion of the cruise(15 more words not shown)
- AIf the strawberries(19 more words not shown)
- BIf there were(25 more words not shown)
- CIf last Friday(23 more words not shown)
- DIf there were(26 more words not shown)
- EThe shipment of(14 more words not shown)
Reading the argument
What if the evidence disappeared over the weekend?
The captain says Friday's contamination would have spread to every strawberry. But the inspection happened on Monday. That leaves several days in which the traces might have disappeared or become undetectable. Finding clean-looking berries later doesn't automatically show they were clean when people ate them.
Picture a contaminant that leaves detectable traces for only a day or two. It could have been present on Friday and no longer show up in Monday's test. That's a possibility the passage hasn't ruled out, not a fact about Cyclospora that we have to know.
The question asks for an assumption that makes the conclusion follow. Then connect the two days: if the shipment had been contaminated Friday, the Monday examination would have detected it. Since the examination didn't, we could exclude Friday contamination and thus exclude this shipment as the source of Friday's illness.
What we’re looking for
The needed rule must reach the evidence we actually have: the result of examining these remaining strawberries on Monday.
Working the answers
- A
This connects contamination with illness, not Friday's condition with Monday's test. Some people could have become ill from contaminated berries on Friday while the traces disappeared before testing. A leaves our timing objection untouched.
- B
This tells us what a positive Monday finding would establish about Friday. But the finding was negative. Knowing that Monday traces would imply earlier contamination doesn't mean every Friday contamination must leave Monday traces. It could disappear, leaving B's rule true while the captain's conclusion was false.
- CCorrect
Friday contamination would have produced traces detected in the actual Monday examination. We have the opposite test result: no traces detected. Under C's rule, Friday contamination therefore cannot have occurred. This closes both the timing gap and the gap between a trace existing somewhere and the exam actually finding it.
- D
This is close, but “some of the strawberries” is not necessarily the several remaining strawberries that were tested. Traces could have remained on berries the captain didn't examine. And saying traces would exist doesn't establish that this examination would detect them. D preserves some physical evidence into Monday without guaranteeing the negative test rules out Friday contamination. C ties the earlier contamination to the actual test result.
- E
Another possible source doesn't eliminate this one. Perhaps contaminated water and strawberries were both plausible suspects. Knowing water could be responsible wouldn't prove the berries weren't. We need evidence excluding the shipment, not merely evidence that another explanation is available.
More Sufficient Assumption questions
- Logical Reasoning Drill Set 10, Question 1Sufficient Assumption
- Logical Reasoning Drill Set 12, Question 4Sufficient Assumption
- Logical Reasoning Drill Set 13, Question 1Sufficient Assumption
- Logical Reasoning Drill Set 3, Question 7Sufficient Assumption
- Logical Reasoning Drill Set 4, Question 7Sufficient Assumption
Learn the LSAT our way
Our platform drills Sufficient Assumption questions at your level and adjusts as you improve.