[讨论]6月份难题集

zhouxh

以下内容转自mba8
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1、9个人考试，分数从0到10，问9个分数的标准方差是否小于3：
A、最大的考试分数不大于9；
B、最小的考试分数不小于6。

2、以知S`4*X`3*Y`7大于0，问SXY是否大于0：
A、Y 小于0：
B、X 大于0。

3、三场表演的参加人数的median是否与其mean相等：
A、参加人数的median是425：
B、参加人数最多的那场与参加人数最少的那场与median相差均为25：

4. 集合S 的标准差是否比T 大？
A）集合S 的MEAN比T大
B）S 有20个数，T有10个数。


5.已知10个数1、3、5、7、9、11、13、15、17、19的标准差，去掉其中的两个数，求剩下8个数的标准差。
（1） 其余8个数的中数为10
（2） 其余8个数的平均数为10


6、93年比92增长M%,94年比93年增长N%,问94比92增长多少? ：（B）
1)MN=60
2)100M+100N+MN=1760

7、有十个连续的整数组成一个集合，是否可确定此集合？
1）负数因子的数量比正数因子的多3个，
2）最大的因子与最小因子的和是-3。


8.有一堆东东X, 每一件的正确与否都用两种方式记录: Paper 和Electrical. 在X中60%有PAPER错误的也有ELEC错误，75%有ELEC错误的也有PAPER错误，X中总共有3%既有PAPER错又有ELEC错。问X中既没有PAPER错也没有ELEC 错的比率。


9、 两个集合S和T, S的range is x and T 的range is y, S 包含T，S and T 的元素均不同，问x>Y?
(1)the number of the fators in S is 7
(2)the number of the fators in T is 6


10.saturday morning某人旅行，如果某天遇上下雨，就在当天下午回家，已知
the three days following saturday each has a 下雨的probability 是0.2,问这个人周一下午回家的概率。(1-0.8)*(1-0.8)*0.2 我觉得应该是0.8*0.8*02，应该是写错了吧。
9.RANGE是波动的范围。所以都不行吧。
8你画张图表看。我做得91/100
7都满足吧。你试看就知道。
6.很明显吧。设第一年为X，然后是（1+M/100）*X，然后类推。
5选E吧。不能确定出剩的数啊。
4.都不行。也是不能确定。
3.三场为200.225.250所以选C。
2.都满足吧。
1.我觉得是D。
大家讨论一下吧。
"

juleyi

2. E agree

8. 94%, you are right.

Thanks for discussion in detail !

____________

------The Seeds of Happiness

sunnY_yueliu

2. On second thought, it should be E. (can not be A, B or C since both A and B are saying the same thing) S^4*X^3*Y^7 > 0 ==> both X and Y >0 or both X and Y <0. Since we can not determine the S, thus don't know the SXY. 8.a=5% and b=4% and c=3% (let c present the product with both E error and P error) So the product without any error =100-4-5+3=94% (since the c has been count twice fro both a and b)

juleyi

1. Thanks for making it clear.
2. 已知S`4*X`3*Y`7大于0，问SXY是否大于0：
A、Y 小于0：
B、X 大于0。
Does S`4*X`3*Y`7 mean: the 4th power of s multiply the 3rd power of x multiply the 7th power of y ?
then we can get different answers by single A or B when s is a positive or negative number ?
8.  有一堆东东X, 每一件的正确与否都用两种方式记录: Paper 和Electrical. 在X中60%有PAPER错误的也有ELEC错误，75%有ELEC错误的也有PAPER错误，X中总共有3%既有PAPER错又有ELEC错。问X中既没有PAPER错也没有ELEC 错的比率。
let a and b the percentage of with error in paper and electrical, then: a*60%=b*75%=3%  ==>  a=5% and b=4%, then the percentage of no error is 91%.

____________

------The Seeds of Happiness

sunnY_yueliu

1. B Standard deviation measures the average difference from mean. The more the values in the series fall apart, the larger the SD will be. So assum there are four 6s and five 10s, then SD will around 2.5, which < 3. On the other hand, if all 9 values are 6.1, then the SD will be zero, which also <3. Thus select B. (use the same method to apply the A, you can only get the SD=0 or SD is around 4.5) 2. Still agree with zhouxh (D) 3. Thanks for the confirmation 5. Agreew with you and zhouxh (E) 8. Still think it should be 94/100 9. Not sure, hope anyone else can clarify Thanks

juleyi

1。感觉是D，请问选B解法？
2。C
3。B
4。5。6。7。8。10同意zhouxh
9、 两个集合S和T, S的range is x and T 的range is y, S 包含T，S and T 的元素均不同，问x>Y?
(1)the number of the fators in S is 7
(2)the number of the fators in T is 6
Does "S 包含T" mean:  S includes the elements of T ?

____________
Human beings come into the world with certain aspirations; they need to know and they need to create. It is the fulfilment of these aspirations that they call happiness. Happiness is like a talent that has to be cultivated.
                               ------The Seeds of Happiness

sunnY_yueliu

I got the different answers as following. Hope the third person can confirm.

1. B
3. B
5. B
8. 94

Thanks!