PrepTest 133, Section 2, Question 20
Whoever murdered Jansen was undoubtedly in Jansen's office(86 more words not shown)
Which one of the following,(14 more words not shown)
- AIf there had(14 more words not shown)
- BJansen's office was(5 more words not shown)
- CNo one but(13 more words not shown)
- DThe fingerprints found(9 more words not shown)
- EThe fingerprints found(9 more words not shown)
Reading the argument
What if someone else was in the office?
We know the murderer was there, and we know Samantha and Herbert were there. That makes them possible suspects. It doesn't make them the only possible suspects. A third person could have visited too.
The evidence does eliminate Herbert. If he had killed Jansen, the police would have found either his fingerprints or his footprints. They found no footprints, and the fingerprints weren't his. Neither of the traces that would have been found if he were the killer was found, so the argument can rule him out.
But eliminating Herbert doesn't finish the case against Samantha. Imagine this as a mystery game: we've crossed Herbert off the list, but what about another visitor? Nothing has yet closed the list at two people. And Samantha's ability to avoid leaving prints doesn't prove that every killer who left no prints must be Samantha.
What we’re looking for
The question asks for a fact that makes the conclusion follow. My prediction is that Herbert and Samantha were the only people in the office that day. Since the killer had to be there and Herbert is ruled out, that would leave Samantha as the only possibility.
Working the answers
- A
We already have a basis for ruling Herbert out: if he were the killer, the police would have found one of his two kinds of prints. A gives us another assurance about finding footprints, but it doesn't eliminate any other visitor as the killer. The missing step is narrowing the possible people.
- B
The argument tells us the killer was in Jansen's office that day, whether or not the murder happened there. Making the office the crime scene still wouldn't tell us who else entered it. The location doesn't close the suspect list.
- CCorrect
Only Herbert and Samantha were in the office that day. The murderer was in the office, so the murderer must be one of those two. The evidence rules out Herbert. Samantha is therefore the remaining possibility. Each part matters: the office requirement limits the group, C closes that group, and the print evidence eliminates one member.
- D
Fingerprints that aren't Jansen's could belong to a third person. Ruling out the victim as their source doesn't establish Samantha as the killer. We still lack the fact that nobody besides Samantha and Herbert could meet the office requirement.
- E
Samantha leaving no fingerprints would be consistent with the description of how she would act if guilty, but consistency isn't proof. Other people's fingerprints could be present for innocent reasons, and another visitor could still be the murderer. E doesn't make Samantha the only possible killer.
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