对费费逻辑27题解释的疑惑

719870465 · 发表于 2011-5-2 02:47:57

These days, drug companies and health professionals alike are focusing their attention on cholesterol in the blood. The more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack. The issue is pertinent since heart disease kills more North Americans every year than any other single cause. At least three factors---smoking, drinking, and exercise—can each influence levels of the cholesterol in the blood.
Which one of the following can be properly concluded from the passage?
(A) If a person has low blood cholesterol, then that person’s risk of fatal heart disease is low.
(B) Smoking in moderation can entail as great a risk of fatal heart disease as does heavy smoking.
(C) A high-cholesterol diet is the principal cause of death in North America.
(D) The only way that smoking increases one’s risk of fatal heart disease is by influencing the levels of cholesterol in the blood.
(E) The risk of fatal heart disease can be altered by certain changes in lifestyle.
答案为E，资料上对它的解释是“A.原文中说，胆固醇越高，生心脏病的可能性越大。A选项的内容是否命题，不一定成立。”我认为这个解释不妥。

应该这么理解。文章说“胆固醇越高，死于心脏病的可能性越大”
A选项说，“胆固醇低，死于心脏病的可能性就低”。举个极端的例子，一点不含胆固醇时，死于心脏病的可能性为90%（很高），含量越高，可能性越大（超过90%）。
也就是说，胆固醇含量低，死的可能性也很大，而且随着含量的升高，死的可能性更大。
如果A选项改成“胆固醇越低，死于心脏病的可能性越低”则就是正确的。
我觉得“胆固醇越高，死于心脏病的可能性越大”这不像是个命题，说不清楚，反正挺迷糊的。希望大牛解释一下。

sdcar2010 · 发表于 2011-5-2 09:34:00

1) 胆固醇越高，死于心脏病的可能性越高 : If higher A, then higher B.
2) 胆固醇低，死于心脏病的可能性就低 : If low A, then low B. Not quite the inverse, but close enough.

So, although 1) is true, 2) might not be true.

zxc1990 · 发表于 2011-5-2 22:23:27

高胆固醇，必然高心脏病发病率
而低胆固醇，仍然有可能因为其他原因导致高心脏病发病率。这也是为何原命题为真无法推出否命题为真

或者从经验考虑。一个人想要死很容易，想要健康活下去却很难。一项高胆固醇指标就可以决定高心脏病风险，而低心脏病几率需要所有体检指标合格来保证，所以一定要保持健康生活方式哦~

sdcar2010 · 发表于 2011-5-2 22:27:17

LS, you cannot add personal knowledge/belief to the reasoning process. It's a no-no in GMATa logical reasoning test.

对费费逻辑27题解释的疑惑

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