#20 - Global

[Jon Denning]

Question #20 is a Global Could Be True, so unlike the previous Must Be True question, here we should be looking for the four (wrong) answers that are impossible! Focus on the absolutes as best you can and these questions get a lot easier.

So let's find the four answer choice options that violate our rules/inferences.

Answer choice (A) seems possible, so I'd hang on to it as I first began this problem, expecting perhaps that the next four were each guilty of some violation.

Of course, (A) is the right answer, so let me quickly show you how it could look (other arrangements are possible):

I H H
F I G
M S T

But I wouldn't start testing it right away! Instead I'd move on to the rest to see if they appear clearly mistaken.

Answer choice (B) is the toughest wrong answer, but it's impossible because it would force F and H together in M: you've used your second I in T with this answer, and filling T without an H means that G cannot go in M (the contrapositive of rule 3). Who does that leave for M, if G and I are out? F and H, breaking a rule. Tricky.

Answer choice (C): this would result in three Is (since I always goes to S), violating our numerical distribution.

Answer choices (D) and (E): both also result in three city visits for one person, which is not allowed for in our 2-2-1-1 distribution.

Let me re-draw your attention to those last three answers, and point out once again how critical it is when you have numerical distributions that you focus on them at all times. Simply knowing that we have a 2-2-1-1 distribution here immediately eliminates those answers (well, in the case of (C) we also need to know that I always goes to S, but the point stands).