OG11 DATA SUFFICIENCY

82. a box contains only red chips, white chips, and blue chips. If a chip is randomly selected from the box, what is the probability that the chip will be either white or blue?

(1)    The probability that the chip will be blue is 1/5

(2)    The probability that the chip will be red is 1/3

我的思路：既然是only，那么1+2就知道white probability，答案应该是C呀

91. By what percent did the median household income in Country Y decrease from 1970 to 1980?

(1)    in 1970 the median household income in Y was 2/3 of the median house hold in X.

(2)    in 1980 the median household income in Y was 1/2 of the median house hold in X.

虽然觉得这个median很可疑，但是又举不出反例来，请哪位举一下。

怎么都不理？是不是问的太白痴了？

82. Let # of red = x, # of white = y and # of blue = z

Q: (y+z)/(x+y+z) = ?

1) 1/5 = z / (x + y + z)  => x + y + z = 5z => x + y = 4z

2) 1/3 = x / (x + y + z) => x + y  + z = 3x => y + z = 2x

1&2 => 2 equations, 3 unknown => inconclusive. 

91.  What do you mean by "觉得这个median很可疑"? 

82题，either white or blue的几率是1- The probability that the chip will be red， 条件2本身就充分了，条件1不充分，故答案为B。

91题，你对median的定义不是很清楚，请先研究什么叫median。