Question

GMAT数学题求答案及解释

In the decimal representation of x, where 0 < x < 1, is the tenths digit of x nonzero?
(1) 16x is an integer.
(2) 8x is an integer.

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.

Answer 1

选b。
题目是说，x是一个0到1之间的数，问当x以小数形式表示时，其十分位是否是非零数字。
先看1，16x是整数，那么1/16,2/16都可以，而1/16=0.0625,2/16=0.125,不能确定x的十分位到底是不是非零。
再看2，8x是整数，那么x至少等于1/8=0.125,十分位是非零数字。
综上，选b。

Answer 2

我觉得C是对的

Answer 3

选b