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1、专业好文档应用概率统计试题A卷参考答案：一、填空题（每空格3分，共30分）1；2. 3.4. 0.7755.61350.50.30.27.；8.9.10.二、判断题（每小题2分，共20分）1错2. 错3. 错4. 对5. 错6. 对7. 错8. 错9. 错10.错三、计算题（共35分）1解： -2分-2分-2分故的分布律为345-1分2. 解：因为随机变量服从正态分布，所以它的密度函数具有如下形式：； （3分）进而，将代入上述表达式可得所求的密度函数为：。 （2分）3.解：（1）设两次都是正品的事件为，-3分（2）设两次都是次品的事件为，-3分4. 解：因为随机变量，且与相互独立，所以利用正态
2、随机变量的可加性（或再生性）可知仍服从正态分布；-（3分）又因为 -（2分）由此可知所求的概率密度为。- （2分）5.解：以表示该样本均值，则-1分从而有 -5分故-1分由此得-1分即-1分所以至少应取35。-1分四、证明题（15分）证明：因为相互独立，所以； （2分）； （2分）； （2分）从而，我们可得由独立性的定义可知：与独立。 （9分）If we dont do that it will go on and go on. We have to stop it; we need the courage to do it.His comments came hours after Fifa
3、 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 exaggerated by the Ivorian and the British media.Blatter, 77, said: It has been decided
4、 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 against the spirit of football and against the visiting team. It is all nonsense.We can do
5、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 (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifas anti-racism taskf
6、orce, 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 Toure, he told BBC Sport.For me its about how he felt and I would like to speak to him
7、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 body, has also ordered an immediate investigation into the referees actions.CSKA said the
8、y 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 descent could happen as early as Sunda.The weather plays an important role in this mission. St
9、arting 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 the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher
10、 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 boundary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly
11、 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 that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the d
12、istance, 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 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begi
13、n 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 to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-sq
14、uare-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 consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).cause there
