#13 - Global, Could Be True, List

[Dave Killoran]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=6469)

The correct answer choice is (B)

Because there is no lack of rules or inferences to apply to this List question, this should be a relatively easy question.

Answer choice (A): This answer choice is incorrect because W cannot appear in a photograph with R or T. Alternately, this answer could be eliminated because when W is in a photograph then Y must be in that photograph.

Answer choice (B): This is the correct answer choice.

Answer choice (C): This answer choice is incorrect because W cannot appear in a photograph with R.

Answer choice (D): This answer choice can be eliminated because when S appears in a photograph, W must also appear in that photograph. Alternately, this answer can be eliminated because T cannot appear in a photograph with S or U.

Answer choice (E): This answer choice can be eliminated because when S appears in a photograph, W must also appear in that photograph. Alternately, this answer can be eliminated because either Y or R must appear in the photograph, or because T cannot appear in a photograph with S or U.

[Benjamin]

Am I missing something here? I'm told that (b) is the correct answer, but I cannot see why any of them would be correct. The rules already say that Raimundo appears in every photograph that Yakira does not.

Am I missing something here or is the question just worded terribly?

[Adam Tyson]

Benjamin,

The third rule in that game is diagrammed as NOT Y -> R (if not Y, then R). In this relationship, R is the necessary condition - when Y is absent, that is sufficient to require R to be selected. Remember, though, that the necessary condition, R, can occur whether or not the sufficient condition occurs. In other words, while R must be selected when Y is absent, R can also be selected even when Y is present. To assume otherwise would be to make a mistaken negation and assume that Y -> NOT R (if Y then not R) or perhaps to make a mistaken reversal and believe that R -> NOT Y (if R then not Y).

That relationship between R and Y means that at least one of those two must appear in every photograph, but it allows for the possibility that both appear together. The only thing that can't happen is for them both to be missing from a photograph.

Hope that made things clear!

Adam

[karlaurrea]

Hello,

Can someone please clarify why the Answer to #13 is B when the original problem states "Raimundo appears in every photograph that Yakira does not appear in"

So my confusion is, is that is R can't be with Y, why is Answer Choice B correct when R and Y are both listed?

Thanks!!

Karla

p.s. what diagram would be used for this game? Or would just listing them, and keeping track of your references would work to see everything?

[Dave Killoran]

Hi Karla,

From what you've said about this question, I think you misinterpreted the third rule, so let's go back and look at that first.

Rule #3. This is a tricky rule, not only because of the wording, but also because the conditional relationship between R and Y is easy to misunderstand. First, let’s diagram the rule:

Y R


I'll note that the above representation is probably the reverse of what you had, and that's what caused the problem. Look over the language of that rule--Y is the sufficient condition, not the necessary condition.

Since our rule diagram contains a negative, let’s also diagram the contrapositive:

R Y

Many students will interpret these two diagrams as reducing to a simple double-not arrow relationship:

Y R

This is not the meaning of the rule! Instead, consider the exact relationship between Y and R: when Y is not in the photograph, then R must be in the photograph; and, via the contrapositive, when R is not in the photograph, then Y must be in the photograph. Thus, when one of the two is not in the photograph, the other must be in the photograph, and that relationship can best be expressed by stating that both cannot be absent from the photograph. The correct double-not arrow diagram, then, is:

R Y

The operating result of this rule is that either Y or R, or both, must appear in each photograph (note that R and Y can appear in a photograph together; the rule does not prohibit this occurrence--and thus answer choice (B) does not cause a violation).

In answer to your question about the game diagram, this is a classic Undefined Grouping game where you don't have a set number of spaces, so your diagram ends up being a representation of each rule, and the inferences that follow--that's pretty much it!

Please let me know if that helps. Thanks!

[karlaurrea]

Yes!!! That definitely makes since! Thanks for clarifying!!

[Stephanie Oswalt]

We have received the following question from a student. An instructor will respond below. Thank you!

I was reviewing and I thought got all inferences and combining correct for a logic grouping game that is: undefined.

For question #13 on Game #3 December 2004 (Page; 350-361, Logic Games Book)

Why is it answer B. Raimundo,Ty, Yakira, Zack: when the rules clearly stated can appear in every photograph except Yakira?
And further t/r neither can appear in any (sufficient word) that Wendy appears, so that should exclude: neither R and Y together cannot be both but no restriction on Selma and Umiko?

[Malila Robinson]

Hi,
I think you are asking the same thing that the second post on this thread asked. If that is the case you may have misinterpreted the third rule. Please check Dave's response- the third post on this thread- to see if that explanation helps you. If not please feel free to ask again, and we can try to narrow down what is confusing you.
Hope that helps!
-Malila

[alberto]

I saw the answer that you sent , Stephanie and, that Malila sent as well. This is Alberto Malila I want to be referred as that if you response to my message okay? I do not want my name real name to be public, Because, since I am sensitive and being part Native American reserved and very shy about my questions on problems since its a public forum just want to keep things quiet and private for me, therefore answer and refer to me as Alberto, thank you? Thank you, Malila. Furthermore,I am not confused, about this part Ms. Malila, but I like to be thorough in my pursuit to diagramming properly and thereafter dealing with answering the questions.

I read fast and I think I think I got it and then I realize not. So, I understand and i did well after Stephanie and Zaria sent me information concerning the photograph game because on the Bird in the forest game similar scenario and I work thru that fine when I slowed down and really watched the wording. I tried to avoid superfluously, those extraneous distractions which is hard but I am learning fast. Anyway,
thank you Ms. Malila.

Good day