代班：2006年12月math原始机经讨论稿3（51-90）12/12纠错更新

jhawaii

55.if C< 0, D> 0, and (C,D), (C,-D) and (-C, -D) are 正方形三顶点, ask which of the following point falls into the same 像限 as the fourth 顶点.

第四个定点应该过第一象限 E)(3,5）

为什么是（3，5）确定的值？

jhawaii

以下是引用phoezi在2006-12-7 8:20:00的发言：
        

71．r/s=?

     (1)r.s is in a line 经过（０，０）（２，４）

　（２）r. s is in a line 过（）（）

　　后面两个点具体数值不记得了，但是没有一个点是原点，我做的时候忘了求直线方程看它是不是过原点了

(1)肯定可以，过原点，则一定为 s=kr.

如果(2)中，也过原点，则D，否则A

但是两点一线，（2）也可以单独成立阿，只要是直线，都可以确定它的斜率亚？

73.a group, 44% are males,75% are athletes, 15%femal are not athletes. what is the percent of males who are athletes

                    Male  Female

Athletes          34     41          75

non ath          10      15          25

                      44      56

34/44

到底应该34%还是34/44阿？

87、n杯沙拉是由橄榄油，某物和水混合的，其中橄榄油:某物:水是2:1:x，问有多少杯水
（1）橄榄油和水的比是1:4
（2）某物的杯数是多少
答案：A

但是A只能确定比值阿，我认为是C，只有当知道其中一个的杯数和各比值，才能知道水的杯数阿？

我的不同意见由红底标出，大家认为如何呢？

wangrui523

75.a school wants to improve the comprehensive ability of students. then it makes students to study English, French, German. 2students are exempt from three courses. 5students are exempt from learning E and F, 8 students are exempt from E and G, 3 are exempt from G and F. 36students are exempt from learning E,22 students are exempt from learning G, 15 are exempt from learning F, how many students are not exempt from learning . the total number is 100

答案应该是41, 我很认真的算了三遍.MM确实多减了个2

87、n杯沙拉是由橄榄油，某物和水混合的，其中橄榄油:某物:水是2:1:x，问有多少杯水
（1）橄榄油和水的比是1:4
（2）某物的杯数是多少

这里面,如果n算是一个已知数的话,就应该选D.(1)可以推出x为8;(2)中,设某物为t杯,则水就有n-3t杯

如果n不算是一个已知数的话,就应该是C.

mccoist

作者：jyou82

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以下是引用chimay914000在2006-12-7 18:17:00的发言：

75.a
school wants to improve the comprehensive ability of students. then it
makes students to study English, French, German. 2students are exempt
from three courses. 5students are exempt from learning E and F, 8
students are exempt from E and G, 3 are exempt from G and F. 36students
are exempt from learning E,22 students are exempt from learning G, 15
are exempt from learning F, how many students are not exempt from
learning . the total number is 100

39：100-36-22-15+5+8+3-2-2

答案不是应该100-36-22-15+5+8+3-2吗???   不需要减多一个2啊!

請
問為什麼 2 students exempted from 3 classes =  +2? 36+22+15= 總exempt課的人 -
5-  8 - 3 = 算了兩次的人因為exempt兩堂 那不是說那兩個人三堂課都免了所以要因為多算了他們一人三次(6堂exemption
其實只有兩個人exempt 3堂)? 那不是因該 - 4? 100 - (36+22+15-5-8-3-4) =  47? 請幫忙解疑謝謝.

记住一个公式，算起来方便些，免得每次画图：A∪B∪C=A+B+C-A∩B-A∩C-B∩C+A∩B∩C

milkship

75.a school wants to improve the comprehensive ability of students.
then it makes students to study English, French, German. 2students are
exempt from three courses. 5students are exempt from learning E and F,
8 students are exempt from E and G, 3 are exempt from G and F.
36students are exempt from learning E,22 students are exempt from
learning G, 15 are exempt from learning F, how many students are not
exempt from learning . the total number is 100

答案应该是41, 我很认真的算了三遍.MM确实多减了个2

agree

87、n杯沙拉是由橄榄油，某物和水混合的，其中橄榄油:某物:水是2:1:x，问有多少杯水
（1）橄榄油和水的比是1:4
（2）某物的杯数是多少

这里面,如果n算是一个已知数的话,就应该选D.(1)可以推出x为8;(2)中,设某物为t杯,则水就有n-3t杯

if we know n, (1) is enough. should choose A

如果n不算是一个已知数的话,就应该是C.

milkship

        84、问中位数，（person per project隐含整数条件）
   

    

      （1）25％的大于等于4
   

    

      （2）35％的小于等于2。
   

    

        答案：C

        77.  which fraction has definite decimal number
   

    

      Ａ．１／（２＾２ ５＾３）Ｂ．１／（２＾３ ３＾４）
   

    

      具体数值不是太记得了，只知道有四个选项分母里面都有３的几次方
   

    

        题目的意思是找有限小数吗？
    

    

        如果是，则A，只除2，5，4，8等一定有限。

I do not understand these two.

milkship

73.a group, 44% are males,75% are athletes, 15%femal are not athletes. what is the percent of males who are athletes

                    Male  Female

Athletes          34     41          75

non ath          10      15          25

                      44      56

34/44

到底应该34%还是34/44阿？

should be 34/44 since the question ask the percentage of males who are athletes.

sigrid920

87、n杯沙拉是由橄榄油，某物和水混合的，其中橄榄油:某物:水是2:1:x，问有多少杯水
（1）橄榄油和水的比是1:4
（2）某物的杯数是多少

这里面,如果n算是一个已知数的话,就应该选D.(1)可以推出x为8;(2)中,设某物为t杯,则水就有n-3t杯

if we know n, (1) is enough. should choose A

如果n不算是一个已知数的话,就应该是C.

不明白, 就算知道是多少杯了, 不是还是只知道比例吗?

rio

75同意41

因为这里说的exempt from E and F不是说only E and F这里的包含了那些三门课都exempt的

rio

79题不应该是32%吗

怎么没人说