電大工程數(shù)學(xué)作業(yè)4答案

1、專業(yè)好文檔工程數(shù)學(xué)作業(yè)（第四次）第6章 統(tǒng)計(jì)推斷（一）單項(xiàng)選擇題 設(shè)是來自正態(tài)總體（均未知）的樣本，則（a）是統(tǒng)計(jì)量 a. b. c. d. 設(shè)是來自正態(tài)總體（均未知）的樣本，則統(tǒng)計(jì)量（d）不是的無偏估計(jì) a. b. c. d. （二）填空題 1統(tǒng)計(jì)量就是 不含未知參數(shù)的樣本函數(shù) 2參數(shù)估計(jì)的兩種方法是 點(diǎn)估計(jì) 和 區(qū)間估計(jì) 常用的參數(shù)點(diǎn)估計(jì)有 矩估計(jì)法 和 最大似然估計(jì) 兩種方法 3比較估計(jì)量好壞的兩個(gè)重要標(biāo)準(zhǔn)是 無偏性 ， 有效性 4設(shè)是來自正態(tài)總體（已知）的樣本值，按給定的顯著性水平檢驗(yàn)，需選取統(tǒng)計(jì)量 5假設(shè)檢驗(yàn)中的顯著性水平為事件（u為臨界值）發(fā)生的概率 （三）解答題 1設(shè)對(duì)總體得到一

2、個(gè)容量為10的樣本值4.5, 2.0, 1.0, 1.5, 3.5, 4.5, 6.5, 5.0, 3.5, 4.0試分別計(jì)算樣本均值和樣本方差解： 2設(shè)總體的概率密度函數(shù)為試分別用矩估計(jì)法和最大似然估計(jì)法估計(jì)參數(shù) 解：提示教材第214頁例3矩估計(jì)：最大似然估計(jì)：， 3測(cè)兩點(diǎn)之間的直線距離5次，測(cè)得距離的值為（單位：m）：108.5 109.0 110.0 110.5 112.0測(cè)量值可以認(rèn)為是服從正態(tài)分布的，求與的估計(jì)值并在；未知的情況下，分別求的置信度為0.95的置信區(qū)間解： （1）當(dāng)時(shí)，由10.95， 查表得： 故所求置信區(qū)間為： （2）當(dāng)未知時(shí)，用替代，查t (4, 0.05 ) ，得

3、 故所求置信區(qū)間為：4設(shè)某產(chǎn)品的性能指標(biāo)服從正態(tài)分布，從歷史資料已知，抽查10個(gè)樣品，求得均值為17，取顯著性水平，問原假設(shè)是否成立 解：，由 ，查表得：因?yàn)?1.96 ，所以拒絕 5某零件長度服從正態(tài)分布，過去的均值為20.0，現(xiàn)換了新材料，從產(chǎn)品中隨機(jī)抽取8個(gè)樣品，測(cè)得的長度為（單位：cm）：20.0, 20.2, 20.1, 20.0, 20.2, 20.3, 19.8, 19.5問用新材料做的零件平均長度是否起了變化（）解：由已知條件可求得： | t | 2.62 接受h0即用新材料做的零件平均長度沒有變化。if we dont do that it will go on and go

4、 on. we have to stop it; we need the courage to do it.his comments came hours after fifa vice-president jeffrey webb - also in london for the fas celebrations - said he wanted to meet ivory coast international toure to discuss his complaint.cska general director roman babaev says the matter has been

5、 exaggerated by the ivorian and the british media.blatter, 77, said: it has been decided by the fifa congress that it is a nonsense for racism to be dealt with with fines. you can always find money from somebody to pay them.it is a nonsense to have matches played without spectators because it is aga

6、inst the spirit of football and against the visiting team. it is all nonsense.we can do something better to fight racism and discrimination.this is one of the villains we have today in our game. but it is only with harsh sanctions that racism and discrimination can be washed out of football.the (lac

7、k of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya

8、 toure, he told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footballs governing b

9、ody, has also ordered an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist insults from fans of cska.baumgartner the disappointing news: mission aborted.the supersonic descen

10、t could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. the balloon, with capsule attached, will move through the lower level of t

11、he atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the boundar

12、y layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembling an olympic diving platform.below, the earth becomes the concrete bottom of a swimming pool tha

13、t he wants to land on, but not too hard. still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. it will be like he is diving into the shallow end.skydiver preps for the big jumpwhen he jumps, he is expected to reach the speed of sound - 690 mp

14、h (1,110 kph) - in less than 40 seconds. like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to earth. but this will not be enough to stop him completely.if he goes too fast or spins out of control, he has a stabilization parachute that can be deployed

15、 to slow him down. his team hopes its not needed. instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).in order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). he will have a reserve parachute that will open automatically if he loses consciousn