Explanation
We should be pleased to see a question about the odd and
even properties of numbers, because we know that we can look at cases to summon
the number properties rules. We know that m
is an integer. Is it odd? On to the data statements, separately first. At a
glance, we know they will both be separately sufficient, by the rules. In
Statement (1), if
is odd, it
could be, say, 9. We see that's awkward. How about 37. Then
and m is 6, which is even. This will hold up
in other cases.
As a tidbit, another way to evaluate this would be to
suppose the contrary. You can say, could m
be odd? Using the rules,
would then be
an odd times and odd, so it must be odd. And adding 1 is adding an odd to an
odd, so
in that case
would be even. But that outcome is not permitted by the data statement, which
states that
must be odd.
Ergo m CANNOT be odd, which means
that it must be even. That example shows another way of evaluating by cases:
you can evaluate by cases whenever you can point to a finite number of
possibilities that will cover the universe of possibilities--in this case, that m is odd or m is even.
Statement (2) is sufficient by the same logic.
The correct answer is (D).
If you believe you have found an error in this question or explanation, please contact us and include the question title or URL in your message.