Self-study
Detective: Laser-printer drums are easily damaged, and Support any nick in a drum will produce a blemish of similar dimensions on each page produced by that printer. ██ ██ ████████ █ ███████ ██ █ ████ ████ █ ████ ██ █ █████ ██ ███ ████████ █████ █ ██████████ █████████████ ████████ ██ ███ ███████ ███████ ██ █████ ██ ███ █████████
Summarize Argument
The detective concludes that he can connect a document to the laser-printer from which it was printed by matching a flaw on the document to the printer’s drum. This is because a flawed printer drum produces a similar flaw on the paper it prints.
Notable Assumptions
The detective assumes that the flaws on the drums are unique and, in extension, that several drums don’t have the same flaw. He also assumes that he can access the flawed drums to compare them with the flawed documents.
22.
Which one of the following, ██ █████ ████ ███████ ███ ███████████ █████████
a
Criminals are unlikely ██ ███ █████ ███ █████ ████████ ██ ███████ ██████████ ██████████
This does not affect the argument. The detective doesn’t claim this method will lead him to the criminal—the detective only claims that the method will lead him to the precise printer from which the blemished document was produced.
b
Drum nicks are ███████ ██ █████ ████ ██ ████████ █████ ██ ██████████ █████████ █████ ████ ███ ██████
This does not affect the argument. The skill required to accurately identify drum nicks is not up for question; the usefulness of the method outlined by the detective is.
c
The manufacturing process █████ ████████ ███ ████ ████ ██ ███████ ██████
This weakens the argument. If several drums have the same nick, the detective would not be able to reliably determine which printer produced the blemished document using his method.
d
Blemishes on documents ███ █████████ ███████ █████████ ██ ██████████ ████ ███ ███████ ████ █████
This does not affect the argument. The detective only argues that a document can be traced when a blemish on a page can be matched with a nick on a drum—if the blemish can‘t be identified in the first place (and thus can’t be connected to a drum), the argument doesn’t apply.
Fighting the hypothetical
Fighting the hypothetical
Answers that aren't relevant because they ignore a hypothetical condition that we're supposed to treat as true. (e.g., the conclusion says "If John is hungry, he'll order pizza" and an answer says, "John isn't hungry")
e
Most suspicious documents ███ ███ ████████ ██ █████ █████████
This does not affect the argument. The detective is only concerned with documents printed from laser-printers.