1. Consider a universe of ten bond from which an investor will ultimately purchase seven bond for his portfolio. If the order in which he buys these bonds is ignored, how many potential 5-bond combinations are there?
3. A random variable with a finite number of equally likely outcomes is best described as a:
A.binomial distribution.
B.discrete uniform distribution.
C.continuous uniform distribution.
A B C
B
[解析] 离散型均匀随机变量(discrete uniform random variable)是指所有可能结果的概率都相等的离散型随机变量,即等可能性的随机变量。从而该种随机变量的离散分布函数F(xn)=np(x),其中n表示分布函数取值的个数。且各种可能结果的概率均为1/N,其中N为所有可能结果的个数。因此,本题的正确选项为B。
4. A recent study indicated that 70% of all college students have a notebook PC. The probability that exactly three college students will have a notebook PC in a random selection of four is approximately:
5. Assume that 45% of candidates who sit for CFA examination pass it the first time in China. Of a random sample of 30 candidates in China who are sitting for the exam for the first time, what is the expected number of candidates that will pass?
8. An analyst determined that approximately 99 percent of the observations of daily sales for a company were within the interval from $230000 to $480000 and that daily sales for the company were normally distributed. The standard deviation of daily sales for the company was closest to:
20. Assume that a population has a mean of 25 with a standard deviation of 3. If a random sample of 60 observations is drawn from this population, the standard error of the sample mean is closest to:
A.0.05
B.0.12
C.0.39
A B C
C
[解析] 样本平均值的标准误差是指样本平均值分布的标准差,其计算公式为:
式中,表示样本平均值的标准误差,σ表示总体的标准差,n表示样本空间的大小。 样本平均值的标准误差
21. Which of the following is least likely to be a desirable property of an estimate?
23. An increase in which of the following items is most likely to result in an increase in the width of the confidence interval for the population mean?
24. A random sample of 64 supermarket customer spent an average of $43. Assuming the distribution is normal and the population standard deviation is $15, the 90% confidence interval for the population mean is closest to:
25. Tuross Online, Inc., sells books by mail. A sample of 16 recent orders showed the mean time taken to send out these orders was 35 hours with a sample standard deviation of 7 hours. Assuming the population is normally distributed, the 95% confidence interval for the population mean is closest to.
26. What is the most appropriate test statistic for constructing confidence intervals for the population mean when the population is normally distributed, but the variance is unknown?
A.The z-statistic at α with n degrees of freedom.
B.The t-statistic at α/2 with n degrees of freedom.
C.The t-statistic at α/2 with n-1 degrees of freedom.
27. The acceptable test statistic for constructing confidence intervals for the population mean of a normally distributed when the variance is unknown and the sample size is large (n≥30) is the:
A.z-statistic.
B.t-statistic.
C.z-statistic or t-statistic, hut t-statistic is more preferred.
33. 某样本A和样本B分别由36个观测值和25个观测值组成,并均取自服从正态分布的总体。已知样本A的平均值为30美元,标准差为8美元;样本B的平均值为34美元,标准差为6美元。试根据上述条件解答问题。 Consider the hypotheses structured for sample A as H0: μ=$26 versus H0: μ≠$26. At a 5% level of significance, the null hypothesis:
A.should be rejected.
B.can not be rejected.
C.can not be tested using this sample information provided.
35. A study was conducted to determine whether the standard deviation of monthly maintenance cost of an airplane is $500. A sample of 25 airplanes of same model had a mean monthly maintenance cost of $4300 and a standard deviation of $545. Using a 10% level of significance, which of the following is the most appropriate conclusion regarding the difference between the hypothesized value of the population variance and the sample variance?
A.The population and sample variances are significantly different.
B.The population and sample variances are not significantly different.
C.There are no tests that may be used to test variance differences in small samples.