Bunuel
A set S contains N elements. Is S a set of distinct consecutive even integers?
(1) The range of S is 2(N-1).
(2) When arranged in increasing order, the difference between any two consecutive terms is 2.
Rephrase the question:>
Is S an arithmetic sequence of even integers? > Note this is quite hard to achieve. We need the set to have even integers only, and the even integers must be consecutive.
> Therefore we focus on trying to DENY that S could be an arithmetic sequence of even integers. (If we successfully deny this, the statement(s) would be sufficient)
Statement 1 Alone:> The range is even. If we have N integers in the set, there would be \(N - 1\) gaps for the range. Thus if S was a set of distinct consecutive even integers, each gap would be 2 and the range is indeed \(2*(N - 1)\).
> However, this does not confirm that all integers in the middle of the range follow the consecutive trend.
> Thus we cannot deny that S could be an arithmetic sequence of even integers; this statement is insufficient.
Statement 2 Alone:> This is the exact scenario of an arithmetic sequence.
> However we did not specify if the terms are all odd or all even.
> We still cannot deny that S could be an arithmetic sequence of even integers. Thus this statement is insufficient.
Both Statements Combined:> The given info still cannot specify if the terms are all odd or all even.
> Combining statements is still insufficient.
Answer: E