Understand the right answer, but have questions about the Kaplan explanation.
It goes: most parts are either A or B. A leads to C. B leads to D.
Thus, most parts are either C, or D, or C+D.

Where does "C+D" come from? I only see most parts are either C or D.

(C in this stem means not humid and D means not cold.)

So it says that choice C: some parts are neither humid nor cold, must be true.

I think C means: some parts are C+D ( dry and hot), and this is mot "must be true". For example, when most parts are dry and cold, and the rest parts are humid and cold.

Any opinions?

I believe I understand what you are asking.

This is a must be false question stem. We are told that:

(1) Diff to do C in Humid
(2) Diff to do O in cold

Country MOST ~1 or ~2

This is why A must be false.

If it were true that half of the country is both C and O, we could not have a majority of the country be either ~1 or ~2.

It appears the Kaplan explanation is simply telling you that an or statement can imply both, which is correct. To say, as the stimulus provides, that a majority of the country is ~1 or ~2 also means that it can be ~1 and ~2.

Unsure if you've already checked here: http://www.manhattanlsat.com/forums/q25 ... 3599248977

Thank you. Yes, the "either or" statement here also means it can be ~1 and ~2. But C says they are ~1 and ~2. So I don't understand why this must be true.

And isn't sometimes in an "either A or B" statement, A and B are exclusive? Whether they are inclusive or exclusive depends on the nature of A and B?

Thanks, I haven't.

This is a must be false question stem. An incorrect answer choice, such as C, does not have to be true. It is simply something that could be true.

Also, sometimes A and B are exclusive. However, on the LSAT, or statements are to be treated as inclusive statements, meaning that both can happen. The exception is when the test writers state A or B, but not both. This is a situation of one is selected/one is not selected.

However, sometimes a situation can be viewed as an exclusive or without the need of a "but not both." I always think of the situation: Either you drink water or you do not drink water. There is not a need for me to state "but not both." It is impossible for both to occur.

Tell me if that does not make it clear.

I wonder why C is not must be true because Kaplan says C must be true. But I guess their explanation is wrong. It's not must be true.

Think of this in terms of a logic game.

We know that:

Country MOST ~Humid or ~Cold

So we know that we have to have at least one those factors be absent, either it must not be hot or not be cold.

It can be true that most parts of the country have both factors absent, but what we know MUST be true is that at least one of those factors is absent.

Answer choice C is stating that some parts have both out. That is not something that must be true. We can have no parts of this country have both factors be out. In other words, we can have all of the country be ~humid and be cold.

Ask any questions you have.