FC5e_eviews Ch04-07 商务统计.pptVIP

Chapter 6 Summary Presented normal distribution continuous random variable Normal Distribution Characteristics Density Function The Standardized Normal Found probabilities for the normal distribution Applied normal distribution to problems The Normal DistributionDensity Function Chapter 6 Summary Presented normal distribution continuous random variable Normal Distribution Characteristics Density Function The Standardized Normal Found probabilities for the normal distribution Applied normal distribution to problems Exercises 从某地区统计中得知，该地区郊区平均每一家庭年收入为3160元，标准差为800元。从郊区抽取50个家庭为一随机样本，平均每年家庭收入为以下数字的概率是多少： （1）多于3000元； （2）少于3000元； （3）在3200元到3300元之间 Exercises 某品牌乒乓球的直径近似服从正态分布，均值1.3英寸，标准差0.04英寸。如果随机选取16个乒乓球： （1）均值的抽样分布是什么？ （2）样本均值小于1.28英寸的概率是多少？ （3）样本均值在1.31~1.33英寸之间的概率是多少？ （4）样本均值夹在怎样的两个对称分布在总体均值两端的值之间时，概率是60%. Exercise 假定已知办公室人员所填写的表格中有5%至少包括一处笔误码。如果我们检查一个由475份表格组成的简单随机样本，其中至少含一处笔误的表格所占的比例在3%和7.5%之间的概率有多大？ Exercise According to Gallup’s poll on personal finances, 46% of U.S. workers say they feel they will have enough money to live comfortably when they retire. If you select a random sample of 200 U.S. workers, a. What is the probability that the sample will have between 45% and 55% who say they have enough money to live comfortably now and expect to do so in the future? Exercise b. the probability is 90% that the sample percentage will be contained within what symmetrical limits of the population percentage? c. The probability of 95% that the sample percentage will be contained within what symmetrical limits of the population percentage? Exercise The fill amount of bottles of a soft drink is normally distributed, with a mean of 2.0 liters and a standard deviation of 0.05 liter. If you select a random sample of 25 bottles, what of the probability that the sample mean will be a. Between 1.9 and 2.0 liters? b. Below 1.98 liters? c. Greater than 2.01 liters? Exercise d. The probability is 99% that the sample mean amount of soft drink will be at least how much? f. The proba