Explanation
Since we have a question about number properties, we will
be inclined to use rules that we know, but examining specific cases can jog our
memory about the rules and confirm our results. Let's go to the data
statements, separately first.
Statement (1) says that
is not an
even integer. In one case,
could be an
odd integer, say 7. Then k would be
14 and k would be even. Is there any
other allowed case in which we get a different answer to the question? Yes, in
fact, there is:
could be a
non-integer, say 7.5 In that case, k would
be 15 and k would not be even.
Statement (1), therefore, does not give us sufficient information to answer the
question. This matter is a good example of evaluating by cases requires not
overlooking important cases. Your best bet of hitting all the cases is to go
through a list: positive numbers, negative numbers, 0, 1, and 2, fractions
between 0 and 1, fractions between -1 and 0, larger fractional numbers, large
positive numbers, and "large" negative numbers. Anyway, Statement (1) is
insufficient.
Statement (2) says that 5 - k is an even integer. We can write this as a pseudo-equation
Subtracting an even number from 5 will always yield an odd
number. That's a rule from the Math Review and we can see that 5-2=3, 5-4=1,
and so on. The integer k is always
odd, so we have sufficient information to answer the question definitively in
the negative. Statement (2) is sufficient.
The correct answer is (B).
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