Q8

[walkerdoreen07]

Hello,

I'm missing something on this game! i printed out the diagram that was posted.
Did not get second diagram.

I don't understand rule 4 and 5. I can't figure out in the second diagram why is H and M is out. I think because "I" must be in and K-f (not sure). I think that is why I got 8, 9 and 10 wrong.
Is rule 4 and rule 5 conditional rules?
for example, q8, i thought b(g) could be the answer too.

help! it seems like simple game.
Doreen

[aileenann]

Hi Doreen - no worries, I'm sure we can clear this up in a jiffy. In my explanation below, I'll assume that you and other readers are also looking at Noah's diagram as posted in this forum for the same game (preptest-40-section-2-g2-a-study-sponsored-by-a-consumer-t210.html).

First, let's consider the constraints you highlighted.

Constraint 4: H ranks better than G *if* both are tested.
Constraint 5: K ranks better than F *if* both are tested.

Conditional constraints can be particularly challenging, because you don't quite know how or where to fit them into the diagram. Here, the thing to remember is that these constraints *only* matter if both of the elements are indeed tested. That said, in this particular game you get an unusual amount of mileage out of these conditional constraints because to some extent they control what is and is not tested. For example, when G is tested first (one of our frames) then we know given that G is first AND that if G and H are both tested H ranks better THAT G cannot be tested - it would simply be impossible to meet all those constraints at the same time. Similarly when F is first (the other frame) then K cannot be tested because it could only be tested if it ranked higher than F - which it cannot when F is first.

Does that make sense?

Now let's look at question # 8. You said you thought (B) could be the answer, so let's check it out. Does G have to be among those tested? No, in fact if we go to the 2nd frame, where H is first, as above, we explicitly know that G cannot be tested.

I have a feeling your other questions probably stem from misunderstanding this constraint, so I won't post solutions just yet for those individual problems. Please let me know if this clears it up or if you'd like me thresh it out a bit more!

[willbrown275]

Hi Aileen,

Your explanations are usually so thorough and lucid (my compliments) but I'm afraid this binary/conditional/number ordering question has me still confused even after seeing the diagram. I gather the M -> F & H is supposed to clear everything up but I find myself seeking a swimming lesson that starts with "this is water", (smiles).

Can you walk me through this?

[aileenann]

Thanks for the follow-up Will. I'd be happy to give a fuller explanation. Which question has got you puzzled?

For the moment, I'll try to thresh out question 8 here. Please do let me know if it would be helpful for you to see another one as well.

Question 8 asks us which cold medicine must be among those tested in the study. Since we have two frames but no additional information, something that must be tested must be tested in either of the two frames. That is, I am looking to figure out what is in regardless of whether F or G is tested first. Well, I know L is definitely tested, but that is way too easy - they told us L is always tested! Similarly, I know I is always tested, again mostly because they told us, so I am not expecting that to be the answer.

If I look at the answer choices, it is indeed the case that neither of the easy answers, I or L, has been provided. So I am going to have to do some more thinking. But I still want to be strategic, so I am going to eliminate H, K, and M right off the bat, because at least in one scenario or both, these medications are out. So we can eliminate C, D, and E from our answer choices.

So now I need to test answer choices A and B, that is tested whether F must be tested or whether G must be tested (and notice I really only need to test one of these options).

Let's first consider F - does F has to be ranked? To see if it has to be ranked, let me see what happens if I don't rank it. Oh wait - now I notice that F is listed as "in" in both of the frames I have, so it must be in. This means that F must be the answer - because it is indeed true that it must be ranked.

There we have it, at least for question 8!

If this doesn't get to what you were looking for help for, please give me a head's up!

[aileenann]

Ok gotcha. So let's just take this step by step.

First thing to understand is why there are two cases. You want to understand that you don't *have* to frame this game to the case where F is ranked first and the case where G is ranked first - it just turns out that if you do frame this (our lingo for splitting up the cases - in this case the 2 cases that depend on who goes first). So I'd recommend that before you follow our frames, you try to do it out without frames just for the basis of comparison. (Also note that if you are in one of our classes or using our self study, you should also have access to a framing workshop we ran separately on this topic).

So the two cases, as you depicted them, are one way of thinking about the game that is not intrinsic to the game - it's a system of notation that makes the ramifications of the two different cases clearer than if we were just to use one diagram.

Ok, so part of what it's important to realize about this notation when using it is that when we are working through an individual question, we need to decide which case applies, or if maybe even both apply. So your first step, once you have put in all the constraints with a framed system, is to decide which case you are in. Is this a case where F definitely goes first? Or is this a case where either of them goes first? And make sure you are not just thinking about F or G when deciding which (or both) case you are in.

Let me know if that makes sense, and we can take it from here! From your comments, I have a sense that your confusion may be stemming as much from the diagram as from the difficulty of the question.

Talk to you soon

[willbrown275]

What I hear you saying is not to get locked into using Noah's example of framing and work this out using the constraints while considering both F and G could go first...and then choose a scenario (either F or G first), yes?

If that is so,

F/G L (I _ _)

would seem to apply.

Using constraint 4 seems to exclude H if G is first because G can't be both first and worse than H. Unclear where H goes if F is first or if it is even tested?

Using constraint 5 seems to exclude K if F is first because F can't be both first and worse than K. Unclear where K goes if G is tested although the slide includes K-F when G is first (which makes sense I guess but why not H-G when F is first?).

Still seems to me that M -> F & H somehow makes a big difference here but I need a bit more direction...

[aileenann]

Hi there,

I didn't mean to say that you shouldn't use the frames - I think you should - they are tremendously helpful. However, it may be easier to understand why and how they work by understanding that they are not intrinsic to this game. You can use a single diagram without framing, and if you are having a hard time conceptualizing it, that should help you think about it in a way that links more directly onto the constraints as they spelled them out for you.

As far as your interpretation of constraints 4 and 5 I think you are dead on the money. In some cases, depending on whether F or G goes first, certain other medications simply can't be included.

Now as far as M -> F & H, consider applying it both to a single diagram and also to frames. Also, think about the contrapositive: not F or not H -> not M. I think this is quite powerful - as your instinct is telling you - because this means that as soon as I am missing either F or H from my medications that are ranked I also can't include M. This might start pushing other elements around - play around with it, especially with the frames and especially keeping in mind the pushouts you already mentioned vis a vis constraints 4 and 5.

Then get back to me and let me know where you are

[hilarykustoff]

Where can I find the framing workshop? I've been looking all over the website but can't seem to find it. Thank you!

[timmydoeslsat]

When you log into the student center, click on self-study. Under the class labs section you will see an advanced framing workshop.