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PrepTest 78, Game 1, Question 5


The fifth question of PT 78 game number one is asking the selection for the project is completely determined if which one of the following is true? So here we are not getting a new piece of information in the question that makes this a global question and we're just looking for an answer. That if true we'll completely determine where every variable goes. The right answer is gonna be one where if it's true you'll know who's in, you'll know who's out and you'll also know who is project leader.

It's very difficult to anticipate the right answer on this kind of question. And so right now I'm just gonna go to the answer choices and I'll test them out. The moment that I feel like the answer does not force a chain of inferences that nails down where every letter goes. The moment I feel like I have a choice about where to put something and I don't know where to put a letter, that's when I'm gonna move on from the answer because it's probably not gonna be correct.

The correct answer will be one where once you do what it says, the rules will trigger and you'll start following a chain of inferences that will nail down where the letters go. So let's take a look. A says neither Q nor S is selected right? If you try to put Q and S out unfortunately, there's no clear thing that happens next.

If Q is out that doesn't necessarily mean that R has to be in and if S is out, that doesn't tell me anything about the T. Rule number two says if S is in, then you have to put T in but that doesn't mean that if S is out, you have to put T out. So right now I'm not inclined to pursue answer choice A further because there's nothing obvious that happens next.

Let's take a look at answer choice B, neither Q nor T is selected. And right now if I put Q out I'm not totally sure what that does but I'm liking this answer because it has me put T out. And according to the contrapositive of rule two, if T is out you have to put S out. So I'm gonna throw S out right now.

And now there's only one out group slot left which is putting a lot of pressure on our letters. Especially since I have rule number 3 here where W being in kicks two letters out. If I only have one out group slot left and putting W in like this means I have to put R and V out. Do you notice the contradiction?

I don't have enough room to put both R and V out when I put W in. So what does that mean about the W right now? Well, that means that the W has to go out. And now that the out group is full, every other letter is rushing into the in group. The X will have to be in, the V will have to be in and the final letter that's remaining is the R the R, V and X will have to be in.

This kicks in rule number 1, if R is in R is got to be project leader. That is why answer choice B would fully determine the selection of the project members. Now in a time situation I would just move on from this question once I did this work and saw that B was correct, but since this is review let's go ahead and see how we might think about the other answers.

C says neither Q nor X is selected and this isn't a particularly attractive answer right now. Because do you notice that putting Q out doesn't seem to trigger anything else and putting x out doesn't trigger anything else because there's no rule about X? So I'm kind of stumped I don't know what the next step is. And on this kind of question if everything is gonna be fully determined, I wanna know what the next step is.

If there's no clear next step, no clear inference, it's probably not going to end up determining everything. Answer choice D says neither R nor W is selected. So if you put R out and W out again, this doesn't do much. Putting R out doesn't mean that Q has to be in, the queue could be out right now and putting W out that doesn't mean anything about the R or the V.

If W was in, then you'd have to kick V and R out but if the W is out then rule number three doesn't mean anything. So none of the rules are triggering, you have to open outgroups slots, I don't know what else to do next that's why I would move on from answer choice D. The same exact thing is happening with answer choice E if you put R out and V out well, great.

We are allowed to put W in now because if W is in then R and V are out but this doesn't necessarily mean we have to put W in. So none of these other rules are triggering that's why E is not attractive. Notice that answer choice B was the only one that ended up having one outgroup slot left and that is what triggered the inference that meant W couldn't be in.

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