We get those inferences through a series of rules interacting with each other,
jordandiam@gmail.com , which Robert walked through. I'll go through them again and try to put them all together for you.
First, every component is attached either by hand or by machine, never by both. Now, take a look at the second and third rules, both of which involve T. W has to be before T, but nothing can be attached by hand before T is attached. That tells us a couple things already: The first component has to be attached by machine (because T cannot be first, and no H can be before T), and W must be attached by machine (because W is before T, and again, nothing attached before T can be an H).
Next, combine that with the first two rules, both of which are about X. X has to be 4th, and exactly two things before X are attached by hand. But now we know that the first one attached has to be attached by machine, not by hand, so when we place X 4th, it forces the second and third components to be those two Hs before the X.
At this point, we know that the first three must be MHH, which answers your question. But we also know that T must be second, because we can't have an H before T but we must have W before T. And if T is second, W is first. The game board is quickly filling up!
If it helps, try thinking about the alternatives. What if, as you suggested, the first three were HMH (and since it's always an H or an M, there's no point to leaving a blank space between the two Hs. Put an M there)? Where would you be able to put T without breaking a rule? If you put it first, then W is not before T. If you put T second, then there would be something attached by hand before T, breaking that rule. Thus, HMH in the first three spaces is impossible! For the same reason, so is HHM. Try it and you'll see!
Logic games are always about connecting rules together and making additional inferences based on those connections. We cannot afford to study each rule only in isolation, but always have to look at the bigger picture and see how they affect each other. That's what they are testing when they get to the questions, and so that's the work we need to do right from the beginning of the game. Find the connections, make the inferences, and build a more complete, accurate, and helpful diagram.
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
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