Q1. In order to test if the mean IQ of employees in an organization is greater than 100, a sample of 30 employees is taken. The sample value of the computed z-statistic = 3.4. The appropriate decision at a 5% significance level is to: A) reject the null hypothesis and conclude that the population mean is not equal to 100. B) reject the null hypotheses and conclude that the population mean is greater than 100. C) reject the null hypothesis and conclude that the population mean is equal to 100.
Q2. Maria Huffman is the Vice President of Human Resources for a large regional car rental company. Last year, she hired Graham Brickley as Manager of Employee Retention. Part of the compensation package was the chance to earn one of the following two bonuses: if Brickley can reduce turnover to less than 30%, he will receive a 25% bonus. If he can reduce turnover to less than 25%, he will receive a 50% bonus (using a significance level of 10%). The population of turnover rates is normally distributed. The population standard deviation of turnover rates is 1.5%. A recent sample of 100 branch offices resulted in an average turnover rate of 24.2%. Which of the following statements is most accurate? A) For the 50% bonus level, the test statistic is -5.33 and Huffman should give Brickley a 50% bonus. B) For the 50% bonus level, the critical value is -1.65 and Huffman should give Brickley a 50% bonus. C) Brickley should not receive either bonus.
Q3. Which of the following statements about test statistics is least accurate? A) In the case of a test of the difference in means of two independent samples, we use a t-distributed test statistic. B) In a test of the population mean, if the population variance is unknown and the sample is small, we should use a z-distributed test statistic. C) In a test of the population mean, if the population variance is unknown, we should use a t-distributed test statistic.
Q4. In a test of the mean of a population, if the population variance is: A) known, a t-distributed test statistic is appropriate. B) known, a z-distributed test statistic is appropriate. C) unknown, a z-distributed test statistic is appropriate.
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发表于 2009-1-13 16:06
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