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Q1.the function f is defined for all positive integers n by the following rule. f(n) is the number of positive integers each of which is less than n and has no positive factor in common with n other than 1. If p is any prime number then f(p)=？
A p-1 B p-2 C (p+1)/2 D (p-1)/2 E 2 answer:A 看不懂啊，为什么呢? ＰＳ：现在ＧＭＡＴ－ＭＡＴＨ的阅读越来越饶了，偶阅读不少都要晕菜拉 Q2.求 2+2+2^2+2^3+2^4+…..+2^8=? answer:2^9 偶觉得是用等比数列拉，但是算的结果不对啊，可能是这两天看ＭＡＴＨ看得大脑有些短路了，哪位路过看过的好心ＸＤＪＭ帮偶解释一下
偶觉得是用等比数列拉，但是算的结果不对啊，可能是这两天看ＭＡＴＨ看得大脑有些短路了，哪位路过看过的好心ＸＤＪＭ帮偶解释一下 Q3.100个数据平均数是6,标准差是D,D是正数.请问加入哪2个数据,这102个数据的标准差会小于D? A,-6和0 B,0和0 C,0和6 D,0和12 E,6和6 答案是E,我头晕,不明白了. Q4.一个冷水管，单独注满池用C小时；一个热水管，单独注满池用H小时，C < H。现在两个水管一起开，注满池用了T小时。 问下列哪个对：I. 0<T<H II. C<T<H III.C/2 < T < H/2 答案：I + III During an experiment, some water was removed from each of 6 water tanks. If the standard deviation of the volumes of water in the tanks at the beginning of the experiment was 10 gallons, what was the standard deviation of the volumes of water in the tanks at the end of the experiment? (1) For each tank, 30 percent of the volume of water that was in the tank at the beginning of the experiment was removed during the experiment (2) The average (arithmetic mean) volume of water in the tanks at the end of the experiment was 63 gallons. 答案是A
[此贴子已经被作者于2008-6-18 17:25:29编辑过] | 
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