数学M/S Paper 2讨论专区

佩琪

u , a , b..这是怎么找得?[data description 的calculate standard deviation by coding method]
通常题目会要求我们用这method来找吗??

harry_lim

u , a , b..这是怎么找得?[data description 的calculate standard deviation by coding method]
通常题目 ...
佩琪 发表于 26-10-2010 06:18 PM

coding method。。。。你看看就好。。。STPM不會出的

佩琪

coding method。。。。你看看就好。。。STPM不會出的
harry_lim 发表于 26-10-2010 06:23 PM

    这一课我们多学了什么??[与form 5 add math比较]

wuhu

回复  wuhu


   嘻嘻...我们拿的科系很像呢     你该不会是拿math s,pp和eko吧
sim91 发表于 26-10-2010 04:51 PM

   对没错~你又懂的~你upper的哦???

佩琪

The variable X has following values :
1,2,2,3,3,4,5,6,7,9
find the percentage of the values which are less than the mean.
[mean=4.2]
怎么算??

peaceboy

The variable X has following values :
1,2,2,3,3,4,5,6,7,9
find the percentage of the values which  ...
佩琪 发表于 26-10-2010 07:41 PM

    1,2,2,3,3,4,5,6,7,9

[mean=4.2]

n(S) = 10
(x<4.2) = { 1,2,2,3,3,4}
n(x<4.2) = 6

P(x<4.2) = 6/10 = 0.6

percentage = 0.6*100% = 60%

佩琪

1,2,2,3,3,4,5,6,7,9

[mean=4.2]

n(S) = 10
(x
peaceboy 发表于 26-10-2010 08:27 PM

，谢谢..我去问allmath了...

佩琪

A and B are two events such that  P（A）=1/2. P(A|-B)=2/3 and P(B|A)=3/7,where
-B is the event 'B does not occur'.
Find P(A n B),P(A u B) and P(B|A).
State with ur reasons ,if A and B are
-independent
-mutually exclusive
完全不明白....!{:2_81:}

peaceboy

A and B are two events such that  P（A）=1/2. P(A|-B)=2/3 and P(B|A)=3/7,where
-B is the event 'B d ...
佩琪 发表于 26-10-2010 09:07 PM

    A and B are two events such that  P（A）=1/2. P(A|-B)=2/3 and P(B|A)=3/7,where
-B is the event 'B does not occur'.


Find P(A n B),P(A u B) and P(B|A).

P(A)=1/2
P(B l A) = P(A n B) / P(A)
  3/7 = P(A n B) / (1/2)
P(A n B) = 3/14


P(A n B) + P(A n B') = P(A)
P(A n B') = 1/2-3/14
             =2/7

P(A l B') = P(A n B') / P(B')
  2/3      = (2/7) / (1-P(B))
1-P(B) = (2/7) / (2/3)
        P(B) = 4/7

P(A u B) = P(A) + P(B) - P(AnB)
            = 1/2 + 4/7 - 3/14
            =12/14
            =6/7   

P(Bl A) = P(A n B) / P(A)
           = (3/14) / (1/2)
            =6/14
           = 3/7

State with ur reasons ,if A and B are
-independent
P(A) * P(B) = 1/2 * 4/7 = 2/7
P(A n B) = 3/14
since P(A) * P(B) not equal to P(A n B) , therefore it is not a independent event

-mutually exclusive

since P(A n B) not equal to zero , therefore it is not a mutually exclusive event

harry_lim

这一课我们多学了什么??[与form 5 add math比较]
佩琪 发表于 26-10-2010 06:37 PM

semi-interquartile range
coding method
stem leaf
mode(formula)........

佩琪

semi-interquartile range
coding method
stem leaf
mode(formula)........
harry_lim 发表于 26-10-2010 09:40 PM

semi-interquartile range??
什么来的,用在什么时候??formula 是???
还有mode的formula我看不懂，能不能麻烦解释一下??
thanks!

harry_lim

semi-interquartile range??
什么来的,用在什么时候??formula 是???
还有mode的formula我看不懂，能不 ...
佩琪 发表于 26-10-2010 10:58 PM

interquartile range = Q3-Q1
semi interquartile range = 1/2(Q3-Q1)


mode的那個

example


classes      Frequency
1-5                10
6-10              8
11-15            20
16-20              7


Mode = L + [d1/(d1+d2)] X C


L是lower boundary....20最大。。。所以是10.5
d1 = 兩個之間的 - before 兩個之間
    = 20 - 8 = 12
d2 = 兩個之間的 - after 兩個之間
     = 20 - 7 = 13
C是class interval = 15.5-10.5 = 5

那麼mode = 10.5 + [12/(12+13)] x 5
              = 10.5 + 12/25 x 5
              = 12.9


第二個方法是畫histrogram找mode出來。。。這個你應該懂的

佩琪

回复 272# harry_lim


    哦...谢谢~！

harry_lim

回复  harry_lim


    哦...谢谢~！
佩琪 发表于 26-10-2010 11:17 PM

不客氣

wuhu

The probability a student is good at economics is 0.8;the probability she is good at both economics and literature is 0.2. Also the probability a student who is good at literature is also good at economic is 0.6.
(a)Mary is a student who is good at economics.What is the probability she is good at literature too?
(b)What is the probability a student is good at literature?
怎么做???

peaceboy

回复 275# wuhu


    The probability a student is good at economics is 0.8;the probabilityshe is good at both economics and literature is 0.2. Also theprobability a student who is good at literature is also good ateconomic is 0.6.

(a)Mary is a student who is good at economics.What is the probability she is good at literature too?
P(E) = 0.8
P(E n L) = 0.2

P(L l E) = P(E n L) / P(E)
           = 0.2/0.8
           =1/4



(b)What is the probability a student is good at literature?

P(E l L) = 0.6
P(E n L) /P(L) = 0.6
0.2 / P(L) = 0.6
P(L) = 0.2/0.6
       = 1/3

sim91

回复 264# wuhu


   hmm.. 对啊   因为我们学校的packet还蛮特别的
   你问的eko题目有点像我学校老师出的题目
   所以才好奇下啦

佩琪

coding method。。。。你看看就好。。。STPM不會出的
harry_lim 发表于 26-10-2010 06:23 PM

    ,考试真的出...好难!!

wuhu

回复  wuhu


   hmm.. 对啊   因为我们学校的packet还蛮特别的
   你问的eko题目有点像我学校老 ...
sim91 发表于 28-10-2010 05:17 PM

   哦~原来如此啊~你upper six 哦~要加油哦~哈哈~

wuhu

回复  wuhu


    The probability a student is good at economics is 0.8;the probabilityshe is goo ...
peaceboy 发表于 27-10-2010 05:42 PM

   谢谢啦~