数学M/S Paper 2讨论专区

kelfaru

回复 219# 数学系

书写的答案答案是
variance=375
94% C.I = (312.5,327.5)
variance 我也是找到和你一样的答案,可是书本答案是375...(还是书本答案错误???)

kelfaru

再一个问题...

It was observed that 40% of the graduate teachers in a country consist of male teachers. In a random sample of 45 graduate teachers in that country, 4 were male science teachers, 16 were female science teachers, 11 male arts teachers, and 14 female arts teachers.

1) By using normal approximation, estimate the probability that there are at least 10 male teachers from 30 graduate teachers chosen at random.

2) Give a 95% confidence interval for the proportion of science teachers in the country who were male.

数学系

回复 222# kelfaru

1) The probability of male teachers is 0.4.
It follows that u = np = 30(0.4) = 12 > 0.5, (small sigma)^2 = npq = 12(0.6) = 7.2 >0.5

Thus, B(30, 0.4) ----> N(12, 7.2) is valid.

P(at least 10 males) = P(X>=10) ----> P(X>=9.5) = P(Z>=(9.5 - 12)/sqrt(7.2)) = ???

2) The estimator for the population proportion of male science teacher is p^cap = sigma X/n and thus the estimate is 4/45.

Thus, the sampling distribution of p^cap is Bi(n=45, p) ----> N(45p, 45p^cap(1-p^cap)) and the P(-z_0.05/2 <=  p^cap - np/sqrt(np^cap(1-p^cap)) <= z_0.05/2) = 0.95.

Thus, 95% confidence interval for p is -z_0.05/2 <=  p^cap - np/sqrt(np^cap(1-p^cap)) <= z_0.05/2 implies that

-z_0.05/2*sqrt(np^cap(1-p^cap) <=  p^cap - np <= z_0.05/2*sqrt(np^cap(1-p^cap) implies ???

数学系

计算的部分也留给你。

xiang911

回复  xiang911

哈哈~你怎么这么说啊...
佩琪 发表于 31-7-2010 03:19 AM

    认识peaceboy真人就懂了。。怪卡。。

芭樂

A survey, on what type of drinks customers would order if they go to a food stall, shows that out of 120 customers, 75 order tea.
(i) Estimate 90% confidence interval for the proportion of future customers who will order tea.
(ii) If the proportion of future customers who order is exactly 65%, calculate the probability that at least one of the next four customers will order tea.

谢谢

佩琪

回复 225# xiang911


    虽然不知道是什么怪法,但你这样说他的话他应该会伤心哦~哈哈

peaceboy

回复 226# 芭樂


    A survey, on what type of drinks customers would order if they go to afood stall, shows that out of 120 customers, 75 order tea.
(i) Estimate 90% confidence interval for the proportion of future customers who will order tea.
(ii) If the proportion of future customers who order is exactly 65%,calculate the probability that at least one of the next four customerswill order tea.
i)
p = 75/120 =0.625
0.625 +- 1.645((0.625 * 0.375) / 120)^(1 / 2) = 0.625 + - 1.645 * 0.0441941738
                                                           =( 0.5523 , 0.6977)

ii)
p=0.65

p(x>0.25) = p (z>(0.25-0.65)/[(0.65*0.35/4)^(1/2)])
                =p (z>-1.677)
               =0.9532

现在才发现当时做错了

答案应该是1-(0.35)^4...

hongji

这次考试的题目...
Alpha Hitech Sdn.Bhd needs to puschase a number of small printing machines immediately,of which there are 2 types,A and B,in the market.
Type A costs RM4000 ,requires two operators and occupies 20 square metres of floor space.Type B costs RM12000,also requires two operators but occupies 30 square metres.
The company has budgeted for a maximum expenditure of RM120000 on these machines.The printing division has 480 square metres of available floor space and work must be provided for at least 24 operators.
It is proposed that the company buys a combination of machines A and B to maximze production ;given that typeA can print 150 sheets per minute and type B,300 sheets per minute.

c)find the number of machines A and B the company should buy to achieve its objective of maximum production(2marks)

d)state the figure of maximum production and he total cost of the purchase of the machines in this case(marks)

peaceboy

这次考试的题目...
Alpha Hitech Sdn.Bhd needs to puschase a number of small printing machines immedi ...
hongji 发表于 26-8-2010 10:12 PM

    4000A + 12000B <= 120 000
2A + 2B >= 24
20A+30B <= 480

z=150A + 300B

然后画graph = =

hongji

那它MAXIMUM IS 3150 SHEETS?

佩琪

请问来临的大考将会考到第几课?!

peaceboy

请问来临的大考将会考到第几课?!
佩琪 发表于 10-9-2010 04:12 PM

    理论上你应该问你学校的老师吧...

佩琪

回复 233# peaceboy


    我自修...学校没老师教啊~

peaceboy

回复  peaceboy


    我自修...学校没老师教啊~
佩琪 发表于 10-9-2010 07:31 PM

    每个学校都不一样的说，如果是我的学校，lower 6大概只考paper 1 chapter 1,2,3,7罢了

佩琪

回复 235# peaceboy


    不好意思的问，大考不都是根据daerah的syllabus 的吗?
还有个问题....请问paper2没出??

peaceboy

回复  peaceboy


    不好意思的问，大考不都是根据daerah的syllabus 的吗?
还有个问题... ...
佩琪 发表于 10-9-2010 11:46 PM

    跟学校的，我的学校lower6还没开始教paper 2

佩琪

跟学校的，我的学校lower6还没开始教paper 2
peaceboy 发表于 11-9-2010 12:11 AM

    ，谢谢你的资讯。感激万分

sim91

想问问各位
你们的math s p2的past year的答案可以在哪里找到嘛
因为我老师只有1991-2004的答案而已
2005-2009的答案她没有

peaceboy

想问问各位
你们的math s p2的past year的答案可以在哪里找到嘛
因为我老师只有1991-2004的答案而已
  ...
sim91 发表于 4-10-2010 03:29 PM

walrein_lim88<<<他好像有

不然就post问题上来看有没有人要解