首先要明确，因为the ration of physicians to total population is about the same in US and Canada，所以可在总手术量中将operation of physician去掉。那么我们可以得到
the USA has 33% more surgeons per capita，and the reason is people in the united states undergo 40% percent more surgenry per capita than do canadians.即因为美国外科医生多33%，所以美国外科手术多40%.
由于很明显我们可以看出，概率被稀释了
假设如果两国病人对外科手术的需求一样，美国医生多33%, 则推出 手术亦多33%
假设如果美国病人对外科手术需求更高，美国医生多33%,则推出 手术应多一个小于33%的数（比如30%）
假设如果美国病对人外科手术需求更低，美国医生多33%,则推出 手术应多一个大于33%的数（比如40%）
陈向东的黄皮逻辑-假设专题第30题 although the ratio of physicians to total population is about the same in the united states and canada, the USA has 33% more surgeons per capita. clearly, this is the reason people in the united states undergo 40% percent more operations per capita than do canadians. the explanation given above rests on an assumption that A. patients in the USA do not have a greater need for surgery than do patients in canada. B. the population of the USA is not larger than that of canada. C. USA patients sometimes travel to canada for certain kinds of surgery. D. general practitioners in the USA do not as a rule examine a patient who is a candidate for surgery before sending the patient to a surgeon. E. there are no unnecessary surgical operations performed in canada. The answer is A. 我选的是D。 完全不理解意思，希望高人指点，谢谢 -- by 会员 cuifeilin (2011/9/7 16:04:34)
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发表于 2011-9-7 16:04:34
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