答案和详解如下： 1.In a two-tailed test of a hypothesis concerning whether a population mean is zero, Jack Olson computes a t-statistic of 2.7 based on a sample of 20 observations where the distribution is normal. If a 5 percent significance level is chosen, Olson should: A) not make a conclusion pending additional observations. B) reject the null hypothesis and conclude that the population mean is not significantly different from zero. C) fail to reject the null hypothesis that the population mean is not significantly different from zero. D) reject the null hypothesis and conclude that the population mean is significantly different from zero. The correct answer was D) At a 5 percent significance level, the critical t-statistic using the Student’s t-distribution table for a two-tailed test and 19 degrees of freedom (sample size of 20 less 1) is ± 2.093 (with a large sample size the critical z-statistic of 1.960 may be used). Because the critical t-statistic of 2.093 is to the left of the calculated t-statistic of 2.7, meaning that the calculated t-statistic is in the rejection range, we reject the null hypothesis and we conclude that the population mean is significantly different from zero. 2.In order to test whether the mean IQ of employees in an organization is greater than 100, a sample of 30 employees is taken and the sample value of the computed test statistic, tn-1=3.4. The null and alternative hypotheses are: A) H0: µ = 100; Ha: µ ≠ 100. B) H0: µ ≤ 100; Ha: µ > 100. C) H0: X = 100; Ha: X ≠ 100. D) H0: X ≤ 100; Ha: X > 100. The correct answer was B) The null hypothesis is that the theoretical mean is not significantly different from zero. The alternative hypothesis is that the theoretical mean is greater than zero. 3.In order to test if the mean IQ of employees in an organization is greater than 100, a sample of 30 employees is taken and the sample value of the computed test statistic, tn-1=1.2. If you choose a 5 percent significance level you should: A) reject the null hypothesis and conclude that the population mean is equal to 100. B) fail to reject the null hypothesis and conclude that the population mean is greater than 100. C) fail to reject the null hypothesis and conclude that the population mean is not greater than 100. D) reject the null hypothesis and conclude that the population mean is greater than 100. The correct answer was C) At a 5 percent significance level, the critical t-statistic using the Student’s t distribution table for a one-tailed test and 29 degrees of freedom (sample size of 30 less 1) is 1.699 (with a large sample size the critical Z-statistic of 1.645 may be used). Because the critical t-statistic is greater than the calculated t-statistic, meaning that the calculated t-statistic is not in the rejection range, we fail to reject the null hypothesis and we conclude that the population mean is not significantly greater than 100. 4.If the null hypothesis is H0: ρ ≤ 0, what is the appropriate alternative hypothesis? A) Ha: ρ < 0. B) Ha: ρ = 0. C) Ha: ρ> 0. D) Ha: ρ ≠ 0. The correct answer was C) The alternative hypothesis must include the possible outcomes the null does not. 5.Jo Su believes that there should be a negative relation between returns and systematic risk. She intends to collect data on returns and systematic risk to test this theory. What is the appropriate alternative hypothesis? A) Ha: ρ < 0. B) Ha: ρ> 0. C) Ha: ρ = 0. D) Ha: ρ ≠ 0. The correct answer was A) The alternative hypothesis is determined by the theory or the belief. The researcher specifies the null as the hypothesis that she wishes to reject (in favor of the alternative). The theory in this case is that the correlation is negative. | 
发表于 2008-4-16 15:23
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