June 2007, Game 4, Question 21

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Transcript

Question 21. Question 21 is another local question. It's gonna give us a new if condition. So it's gonna take a new sketch that we add that condition to. The new condition here is that if all three centers do three things, so fill in three blanks under each center.

Now, as we learned in the last question, if center one and two are both doing three things, it's going to be the same three things. Which means that center three is going to have to do the solitary plastic, because we can't put it in both one and two because we only get one of them. If center three is doing plastic, that means that centers one and two are both gonna have to do glass, because once you do plastic, you can't do glass.

And anything that's one is also a two. Also, as we learned back in question 20, since we have two spaces left and three things to fill them, n, t, and w, and by rule one if we get rid of n, we also have to get rid of w. There's no way to get rid of n because if you did you would be one item short for the two spaces that are left.

So in question 20, n went to centers one and two, now it's going to have to go to all three centers because all three centers have two spaces left over they need to fill. And just like in question 20 that means that center one and two, they'll do the same thing, either wood or tin. Center three will do whichever one they don't do.

With the sketch finish, we go on to the answer choices. With it could be true, it's best to just to go answer choice by answer choice looking at your sketch. Answer choice A says, that only center two does glass, and we know from our sketch that center one and two are both doing glass. Answer choice B says that only center three does newsprint.

We know from our sketch that all three centers are doing newsprint so cross that out. Answer choice C says that only center one does plastic. We know that center three is the only one doing plastic not center one. Answer choice D says that only center three does tin, and that is something that could be true.

It could be that central three does tin and center one and two each do wood. So since we found what could be true we have our answer. Just for learning purposes, answer choice E, why is it not right? Well, answer choice E says only center one recycles wood, and we know that whatever one is doing two is also doing and vice versa. So it can't be that center one is the only one doing wood.

If it were doing it, center two would be doing it as well. That means the answer is D. On to the next question.

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