请教一道数学题，谢谢！

huangruiyan

请教各位牛牛

Q30:

Joanna bought only $0.15 stamps and $0.29 stamps.  How many $0.15 stamps did she buy?

(1)     She bought $4.40 worth of stamps.

(2)     She bought an equal number of $0.15 stamps and $0.29 stamps.

                  

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.

答案是D  ,但是我不清楚的是，为什么条件2也成立呢，

hgconnie

2单独不成立的.1单独成立.

选A吧?

dancingcandy

我也觉得选A，哪里的题，答案一定对吗？

huangruiyan

GWD 31上的第一套数学题目，答案居然是D

小W

为啥不是C？

ginnygy

条件12合并才成立啊,单独条件12应该都不成立呀.题目的意思应该是JOANNA只买了０．１５美圆一张和0.29美圆一张的邮票,那么她买了多少张0.15美圆一张的邮票呢?设0.15X张,0.29Y张,

(1)0.15X+0.29Y=4.4

(2)X=Y

所以两个单独都不成立,合并才成立啊,答案是不是有啥问题

aaron22

你们忽略了一个隐藏条件，x和y都是整数

我费解的是这种题判断起来很费时间，有没有比较好的方法

无敌可爱多

GWD很多题是错的，LZ做做就好