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#11 - John works five days each week except when on vacation

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Complete Question Explanation

Assumption-SN. The correct answer choice is (D)

The premises in the stimulus establish the following logical relationship: "If there are holidays or vacation, John works less than five days in a week. If neither holidays nor vacation are present, John works five days per week." We are told that last week there were neither holidays nor vacation. The obvious conclusion is that John worked five days last week. We know that Friday he worked as a blacksmith. But how can we be sure that his other days of work were Monday through Thursday? Why are we so quick to dismiss the possibility that he worked on Saturday or Sunday? This is the missing assumption.

Answer choice (A): Apply the Assumption Negation test. Even if John sometimes takes a vacation of more than one week in length, it doesn't matter for the argument: we know that John had no vacation last week, so any consideration of vacation is irrelevant.

Answer choice (B): The argument is not really concerned with the amount of time that John worked on individual days. The argument is only making a claim about the identity of the individual days when John indeed worked.

Answer choice (C): Like choice (A), this statement is irrelevant. We know that neither vacation nor holiday occurred last week, so we have no reason to care about vacation or holiday.

Answer choice (D): This is the correct answer choice. Without the statement in this answer choice, it becomes very possible that John worked on days besides Monday through Thursday.

Answer choice (E): Apply the Assumption Negation test: What if there were some (at least one) days last week in which John worked both jobs? Would this destroy the author's argument? No: it is conceivable that John could have worked his insurance job on Monday, Tuesday, Wednesday, Thursday; and that John worked the blacksmith job on Thursday and Friday. This story is perfectly consistent with the premises of the stimulus.
egarcia193
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Hi,
I guessed on this question, I really didn't understand this question at all and it, in fact, reminded me almost of a logic game question. is it possible to have the stimulus broken down into pieces I am just not understanding what it is telling me and what type of assumption I am looking for in this question.
Adam Tyson
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Sure thing, egarcia! This stimulus is conditional, as indicated by the necessary condition indicator "except". When that is present, it indicates a necessary condition (to the right of your conditional arrow) and the other condition in the stimulus is NOT the sufficient condition. Rather, the NEGATION of that other thing is sufficient. We call that extra step the Unless Equation TM. So the diagram of the first sentence is this:

John works 5 days :arrow: Vacation OR National Holiday

(If John does not work 5 days then he is on vacation that week or else there is a national holiday, or maybe both)

The contrapositive is:

Vacation

AND :longline: :arrow: John works 5 days

National Holiday

(If there is no vacation and there is no national holiday, then John has to work 5 days that week)

The stimulus then tells us that the original necessary conditions did not occur - there's no holiday and he's not on vacation. In other words, we have met the sufficient condition for the contrapositive, and can therefore prove that John worked 5 days that week.

Now the question is, WHICH 5 days? We know John works as a blacksmith on Fridays, and in the insurance company 4 other days. The author concluded that he worked there Monday through Thursday, but how would he know that? Who says it has to be THOSE 4 days? Couldn't he work Saturday, or Sunday, or both?

The assumption here is a defender assumption, one that fights off an attack. If we are saying "but wait, he could work the weekend, so maybe it isn't Monday through Thursday", the author must have assumed that it was NOT the weekend, fending off that objection. That gets you answer D, the correct answer here.

To prove it, try the Negation Technique TM on that answer - what if John DID work Saturday or Sunday or both? Then the claim that he worked Monday through Thursday would be completely false, since he worked 5 days including Friday.

With that big, juicy conditional claim just ripe for the picking in the first sentence, go ahead and diagram it. That way, with a little practice, arguments like these will become much clearer, and picking right answers will be about as easy as playing connect-the-dots.

Keep at it!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
Follow me on Twitter at https://twitter.com/LSATadam
edacyu
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Hi!

I'm currently enrolled in the LSAT Live Online course and working through Lesson 5. The last question in this section in my book, however, is #20, so I'm wondering where the remainder of these questions can be found for practice :-D
Stephanie Turaj
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Hi edacyu!

Thanks for the question! Those additional practice questions are located in your Online Student Center (older versions of the course books had them in the book as opposed to online -- sorry for that confusion!)

I am sending you an email with instructions on how to find those questions!

Thanks!
rhaus1
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Where is this question in the book? i only see 20 questions for the assumption question. After the 20th question it goes into the strengthen/justify the con/ and assumption identify drill
Stephanie Turaj
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Hi rhaus!

Thanks for the question! Those additional practice questions are located in your Online Student Center (older versions of the course books had them in the book as opposed to online.)

I am sending you an email with instructions on how to find those questions!

Thanks!