GMAT
题目
If M is a positive integer such that average (arithmetic mean) of 31, 33, M, 36, and 37 lies between 40 and 43 (both inclusive). What is the number of possible values of M?
解析
\[
40 \leq \frac{31+33+36+37+M}{5} \leq 43
\]
\[
40 \leq \frac{137+M}{5} \leq 43
\]
\[
40 \times 5 \leq (137 + M) \leq 43 \times 5
\]
\[
200 \leq (137 + M) \leq 215
\]
\[
63 \leq M \leq 78
\]
从63到78（包含两端）的整数个数为：\(78 - 62 = 16\)
答案：选项B
在线客服
官方微信
公众号