#10 - Global, Must Be True

[Dave Killoran]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=1572)

The correct answer choice is (B)

In our initial diagram, only Y and S are fixed, and these are the two trucks that meet the criteria. Consequently, answer choice (B) is correct.

[lathlee]

I get this question wrong twice and I feel like this isn't my fault.

the wording of the question: " For exactly how many of the seven trucks can one determine exactly how many trucks arrived before it? "

What the heaven does "IT" indicates and "before it" cuz I get y and s arrive at what timing spot 4 and 6. but so what? that is not what this question is asking, I feel like. but you guys, the administrators, are saying that's what the question is asking. I don't get it.

[Jon Denning]

Yeah, this one trips up a lot of people! All it's asking is for the number of trucks whose positions are fixed: that's what it would take for us to know EXACTLY how many trucks arrive before it.

Consider S in 6. We know for sure that exactly five trucks arrive before S, so it is is one of the trucks that satisfies what we're looking for in this question. Ditto with Y: since Y is always in 4, then there are always exactly three trucks that arrive before it.

But what about a truck like T? Since T can go in either 5 or 7, we can't know exactly how many trucks arrive before it! If T is in 5 then four trucks come ahead of it...but if T is in 7 then there are six trucks before it. So since we can't know exactly, T does NOT work for this question.

That's why the answer is two: only Y and S are fixed, so they're the only trucks for which we can answer this question.