gwd-26-31答案有疑问！

梦不落

Q31:

One kilogram of a certain coffee blend consists of x kilogram of type I coffee and y kilogram of type II coffee.  The cost of the blend is C dollars per kilogram, where C = 6.5x + 8.5y.  Is x < 0.8?

(1)         y > 0.15

(2)         C ≥ 7.30

the answer is B, however i think it should be E.

C>=7.30

so， 6.5x+8.5y>=7.30

so， 6.5x+8.5(1-X).=7.30

so， x<=0.8

so， x could be equal to 0.8

so， the condition 2 is not sufficient

can anybody help me out here? thanks!

why is it that I sometimes can not type chinese???

LMG1

6.5x+8.5(1-x)>=7.3

so 6.5x+8.5-8.5x>=7.3

so-2x>=-1.2

sox<=0.6

of course must <0.8

梦不落

唉。。我又马虎了。。这套题我错了8个，全都是马虎。而且全都是这种题型。。。

可怎么办啊。。。

回来者023

the answer of this question is E you are right, be confident! buddy

梦不落

倒。。。楼上的兄弟，应该是选B..你也马虎了吧

katrinaxy520

哎，我漏掉了１－Ｘ＝Ｙ这个条件，搞的选Ｅ去了．．．