xdf蓝皮书-ds-89和90

新东方蓝皮书上面231页，data sufficiency上的89 90 题

89,which is the median number of employees assigned per project for the projects at company Z?

    (1)25 percent of the projects at company Z have 4 or more employees assigned to each project.

    (2)35 percent of the projects at company Z have 2 or fewer employees assigned to each project.     答案 C

90.One kilogram of a certain coffee bleand consists of x kilogram of type I coffee and y kilogram of type 2 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答案 B

不知道思路是什么。。。。请大家指教！！谢谢大家了！！

89题我也没想明白，感觉这道题可以用概率的正态分布去解，那是超纲的啊，肯定有范围内的方法的，希望高人赐教！

90题。一公斤的某咖啡是X公斤I咖啡和公斤II咖啡的混合物。混合咖啡的价格是每公斤C美元。 当C=6.5X+8.5Y时， X<0.8?

由题干可知 X=1-Y

(1) Y>0.15, X=1-Y<0.85 不能推出 X<0.8

(2) C=6.5x+8.5y>=7.30,  C=6.5x+8.5(1-x)>=7.30, x<0.6  ，可以推出X<0.8

所以选B