#9 - Global

[Jon Denning]

Question #9 is another Global question (like #7), but this time we have a Cannot Be True. That's a gift, because it means the right answer should stand out: it's the only absolute, specifically because it's the single answer choice that will always violate a rule (cause an issue), in this case by trying to fill the third spot.

Let's find it.

You should know by now that the third position is either filled by M (so B is possible and can be removed), or else is left open to the LNOS group with MTP in 5-7.

Clearly for this question we're in the latter situation with LNOS as the four variables filling the first four spots.

So which of those four cannot be in 3?

If you made the early inference that S cannot be third (more on this in a sec) you're done. (E) is the right answer and you can move on.

It's a tricky, and somewhat obscure, inference though, so if you didn't catch it up front now's your chance to discover it! The best way to do that? Quickly (!) cycle through those four variables until one causes a clear problem. Here's how that looks:

L 3: This puts O in 1, N in 4, and S in 2. That works. (A) is out.

N in 3: This puts L ahead of it, and L must be in 2 with O in 4 so they're appropriately separated. S is in 1, and
this works too. (C) is out.

O in 3: This puts L in 1, and now we have options for N and S. They're in 2 and 4, but we don't know their order.
Still, both orders will work, so (D) is out.

Finally, S in 3: This means the L/O __ O/L block has to go in 2 and 4...and now we're in trouble. Regardless of
L and O's order, N would have to be in 1, which can never occur (must be after L). So S in 3 is a problem,
and (E) is correct.

If you didn't have that inference up front, which is understandable, you've got it now and should add it to your main diagram(s)!