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。
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