Explanation
This question is rather simple-looking. Let's head to the
data statements, evaluating them separately at first.
Statement (1) tells us that
. That means
. Does that fact allow us to answer
definitively?
It may appear to allow us to answer the question definitively in the negative.
To be sure, we can analyze by cases.Case I:
. That is permitted because
. In this case, it is true that
, because
, so the answer would be "yes." Case II:
. That case is permitted, as the sum is still
greater than zero. In this case, is
? No;
is false. We
have obtained different answers from allowed cases,
so we don't have sufficient information to answer the question definitively.
Statement (1) is insufficient.
Statement (2) tells us that w to the v power is
negative. The only way that could happen is if w itself is negative. In fact, this data statement allows our case
, where it's true that
, and the answer is "yes." Could v be less than w, which has to be negative? Yes;
could be
, a.k.a.
. That's negative, so it's allowed by Statement (2),
and it gives a "no" answer to
, because -3 is more negative than -2 and is hence
less than -2. So, again we have a "yes" and a "no" in permitted cases.
Statement (2) is insufficient.
Combining the statements, we're tiring a little of
constructing cases, so we prefer to use preexisting cases that are allowed by
both statements. As we've seen, the case
is allowed by
both statements, and it gives us a "yes" to the question of
. The other cases are no longer allowed. We look at
Statement (1). Since w has to be negative now, v will
have to be positive; that's the only way to get the sum above zero, as
Statement (1) requires. And if w has
to be negative and v has to be
positive, that means that, in all allowed cases, v will be greater than w.
We can answer the question definitively in the affirmative. The statements are
sufficient together and the correct answer is (C).
This was a typical finish to a question in which rules,
such as number properties rules, were in play in the question, but we didn't
necessarily know what those rules were. What will happen is that you can
analyze by cases and you may hit a moment when you notice a regularity. Here it
was the fact that, when the statements were combined, v had to be positive and w negative.
Keeping an eye out for conclusions that you can draw will be superior in
general to attempting to analyze by cases through brute force.
Again, in this question, the correct answer is (C).
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