preptest07 math2 第150题

dizzyboy

看似很容易，可是我做错了，而且还不知道为什么。
150. If n is an integer between 3 and 9, what is the value of n?
(1) On the number line, the distance from 3 to n is 2/3 of the distance from 3 to 9.
(2) On the number line, n is 10 units to the right of -3
我选了B，而正确答案是D. 请大侠解答！谢谢。

dizzyboy

On the number line, the distance from 3 to n is 2/3 of the distance from 3 to 9

the distance from 3 to 9: 6
2/3 of the distance from 3 to 9: 4
the distance from 3 to n is 2/3 of the distance from 3 to 9: the distance from 3 to n is 4, then n is 7 or -1.
n is between 3 and 9: then n = 7

Sufficient

-- by 会员 sdcar2010 (2011/6/23 6:41:18)

看来我今天题做得有点儿晕了，这么简单的都错...