数学M/S Paper 2讨论专区

sim91

walrein_lim88
peaceboy 发表于 4-10-2010 06:06 PM

   我本来是打算和他买solution的
   可是他说有题目没空写完答案啊(math s p2)   你的提议也不错啦 我不会的就会post上来找你们帮忙啦
   希望你们能帮忙解救我 因为拿math s的人实在太少了

數學神童

It is found that 5% doctors in a particular country play golf. Find , to 3 decimal places, the probability that , in a random sample of 50 doctors, two play golf.
Hence,state the sampling distribution of the proportion of the doctors who play golf, and construct 98% confidence interval for the proportion.

peaceboy

回复 242# 數學神童

i.50C2 (0.05)^2 (0.95)^48 =0.261

ii.x~N(0.05 ,  0.0475/50)

p(x<a) = 0.98
p(z<(a-0.05)/(0.00095)^(1/2)) = 0.98
p(z>(a-0.05)/(0.00095)^(1/2))=0.02
(a-0.05)/(0.00095)^(1/2) = 2.054
a-0.05 = 0.0633
a=0.1133
confident interval =(0 , 0.1133)
不懂对没有

數學神童

the continuity correction is not 1/(2n)?

peaceboy

the continuity correction is not 1/(2n)?
數學神童 发表于 12-10-2010 07:59 PM

    对hor，忘了....

數學神童

A manufacturer produces a new type of paint.He claims that the paint has 0.04% lead content by weight.A random sample of 25 tins (1kg per tin) of the paint is analysed to determine the lead content.Sample mean and standard deviation of the lead content in kg of paint are 0.38g and 0.1g respectively.
a)construct 99% confidence interval for the mean lead content in kg of paint.State your assumption

peaceboy

A manufacturer produces a new type of paint.He claims that the paint has 0.04% lead content by weigh ...
數學神童 发表于 12-10-2010 10:02 PM

    further math T的吧，n<30好像是用t-distribution的，没学过....
除非assume它是normal distribution

sim91

hmm...我想请问price indices和weighted prices indices有什么不同呢?????

peaceboy

hmm...我想请问price indices 和 weighted prices indices有什么不同呢?????
sim91 发表于 13-10-2010 03:59 PM

    多了weighted

weighted prices indices 是要乘weightage 的，通常price index的weightage 是quantity ，相反quantity index的weightage是price


Paasche and Laspeyres price indices<<<<这两种都是weighted prices indices

harry_lim

laspeyres & paasche >>>背就好了

price indices跟這個差很多咯

sim91

这个题目能教教我怎样做嘛看不懂它问什么啊？？？

The mass of a box of chocolate cereal is distributed normally with mean 100g and standard deviation 2g.Calculate the probability that
a)three box of chocolate cereal chosen at random,each has mass less than 98g
b)three box of chocolate cereal chosen at random have a total mass exceeding 305g
c)out of three boxes of chocolate cereal chosen at random,exactly two have a mass greater than 98g each while the mass of the remaining box is greater than 105g

peaceboy

回复 251# sim91


   The mass of a box of chocolate cereal is distributed normally with mean 100g and standard deviation 2g.Calculate the probability that
a)three box of chocolate cereal chosen at random,each has mass less than 98g



P(x<98) = p(z<(98-100)/2)
            = p(z<-1)
            = 0.1587


0.1587 * 0.1587 * 0.1587 =0.003997               



b)three box of chocolate cereal chosen at random have a total mass exceeding 305g
E(x+x+x) = E(x)+E(x)+E(x)
              = 300


Var(x+x+x) = Var(X) + Var (X) +Var(X)
                 =4+4+4
                 =12


P(x+x+x > 305) = P(z> (305-300)/(12)^(1/2))
                       = P(z>1.443)
                       = 0.07451




c)out of three boxes of chocolate cereal chosen at random,exactly two have a mass greater(没有打错？) than 98g each while the mass of the remaining box is greater than 105g


P(x>98)= 1-0.1587
           = 0.8413


P(x>105) = P(z>2.5)
             = 0.00621


0.8413*0.8413*0.00621 * 3!/2! = 0.0132






大凡这类的都不是很肯定答案

sim91

回复 252# peaceboy


    谢谢你的帮忙啊 总算有点明白了
    那个题目没写错。。。

peaceboy

回复 253# sim91


    我比较在意的是，我的答案对不？

sim91

回复 254# peaceboy


    嘻嘻...我也不清楚耶
    这是老师给我们做的latihan来的
    星期一他才讨论..

peaceboy

回复  peaceboy


    嘻嘻...我也不清楚耶
    这是老师给我们做的latihan来的
   ...
sim91 发表于 23-10-2010 09:00 PM

    因为答案不是很美的关系，所以感觉怪怪的
这类题目不能check答案，很没有信心的说....

wuhu

请问下做么有的histogram前面一开始很像被电炸到啊???

peaceboy

回复 257# wuhu


    坏事作太多被雷劈



那个是因为它的scale 跳很多

比如说你的scale 本来是 1cm : 10


_____l_____l_____l_____l_____l_____l_____l_____l
        0       10      20      30     40      50      60      70

那么你的graph x-axis应该是这样plot的
不过如果你跳太多
直接从0到100，我们就这样放

_____l__N__l_____l_____l_____l_____l_____l_____l
       0        100    110    120    130     140   150     160

wuhu

回复  wuhu


     坏事作太多被雷劈



那个是因为它的scale 跳很多

比如说你的scale 本来 ...
peaceboy 发表于 25-10-2010 07:26 PM

哦~原来是这样啊~谢谢啦~

sim91

回复 259# wuhu


   嘻嘻...我们拿的科系很像呢     你该不会是拿math s,pp和eko吧