Now that you’ve gotten a little more confident, we’re going to give you the opportunity to practice "without the training wheels." When you want to check your work, you can turn to the solutions at the end. If you aren’t familiar with some of the mathematical concepts, make a note to pay particular attention to that chapter in this book; this practice set covers a wide range of topics tested on the GMAT.
On all data sufficiency problems, the answer choices are the same (as you’ve learned). We’ve put them here for your reference.
Ａ. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Ｂ. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
Ｃ. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
Ｄ. EACH statement ALONE is sufficient.
Ｅ. Statements (1) and (2) TOGETHER are NOT sufficient.
What is the average of a list of n consecutive integers
(1) The smallest number in the list is 5.
(2) n=8
参考答案：C
解析：Statement (1) tells us the smallest number, but not how many numbers are in the list. It is not sufficient. Cross off A and D.
Statement (2) tells us the value of n, so the question becomes: What is the average of a list of 8 consecutive integers Since those integers can be large, small, or even negative, we have no way to tell what the average is. Statement (2) is not sufficient, so we can eliminate B.
Now let’s put the two statements together. If we know that 5 is the smallest number in a list of 8 consecutive numbers, then we can easily reconstruct the list and find the average. So the statements are sufficient when put together, and the answer is C.