Q5

 
jyup1982
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Q5

by jyup1982 Wed Aug 03, 2011 2:25 am

Q5 says If the inspection is scheduled for the day immediately before the inspection of F, which one of the following must be true about the schdule?

I think I'm not getting the point of the question or I am totally lost in setup. Could anyone plz help me with the question? Why D is the answer?
 
timmydoeslsat
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Re: Q5

by timmydoeslsat Wed Aug 03, 2011 11:38 am

This can be seen as a global diagram for this game

Image

The checkmarks indicate that the variable was used in a rule. The boxed-in variable is one that is completely random. It has no rules governing it. That variable is H.

There are 4 rules. I built in the first rule into my diagram.

The second and third rules can be combined.

The fourth rule is a conditional statement. It is important to note the contrapositive of this rule, I do it in my head, but for clarity it is:

~Q (5) ---> ~G (3)

(~ = not)

Question number five gives us a local condition that can be initially noted as this:

Image

What else can we infer from this local rule? We know that Q is immediately before R. We also know that J comes at some point before Q.

Image

The next thing we can consider is the placement of this " J > block "

We know that F must be either first or sixth. In this case, it must be sixth because it has variables that come before it.

Image

We know that the block indicates that Q and R are directly next to F. We know that J must simply come before those variables.

Image

We are not done looking at the rules that have been giving to us.

It is important to consider that we only have three variables left to place: J, which at this point has no rules governing it anymore, H, which has no rules governing it, and G, which does have one rule governing it. When G is third, QR fill spots five and six.

We know that in this scenario QR do not fill in those spots, which means, via the contrapositive, that G will not fill the third spot. That means the third spot has only two contenders: J and H.

Image

This is represented by choice D. This is something that MUST be true.
 
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Re: Q5

by VladimirI226 Wed Nov 28, 2018 3:32 pm

I understand that G can not be third. I would like to know why Answers A, B, C that deal with position 1 and 2 are not the correct answers. How are those answers eliminated as viable options. Element J,G, and H can easily be placed in position 1 and 2. I guess this is the difference between the could be true and must be true answer.