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ch09 - Ch.9...

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Ch. 9 Estimating the Value of a Parameter Using Confidence Intervals 9.1 The Logic in Constructing Confidence Intervals about a Population Mean where the Pop Std Dev Is Known 1 Compute a Point Estimate of the Population Mean MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Private colleges and universities rely on money contributed by individuals and corporations for their operating expenses. Much of this money is put into a fund called an endowment, and the college spends only the interest earned by the fund. A recent survey of eight private colleges in the United States revealed the following endowments (in millions of dollars): 74.8, 53.3, 242.2, 499.2, 124.7, 151.2, 92.7, and 211.4. What value will be used as the point estimate for the mean endowment of all private colleges in the United States? A) 181.188 B) 1449.5 C) 207.071 D) 8 SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 2) The grade point averages for 10 randomly selected students in a statistics class with 125 students are listed below. What can you say about the mean score μ of all 125 students? 3.1 2.3 2.7 1.8 3.2 3.0 2.0 3.4 2.2 2.6 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 3) A point estimate is the value of a ______________ that estimates the value of a _______________. A) Statistic; parameter B) Parameter; statistic C) Random variable; statistic D) Random variable; parameter 2 Construct and Interpret a Confidence Interval about the Population Mean MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Compute the critical value z α /2 that corresponds to a 95% level of confidence. A) 1.96 B) 2.575 C) 2.33 D) 1.645 SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 2) In a recent study of 95 eighth graders, the mean number of hours per week that they watched television was 18.7. Assume σ = 5.5 hours. a) Find the 95% confidence interval of the mean. b) If the standard deviation is doubled to 11, what will be the effect on the confidence interval? MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 3) In a sample of 10 randomly selected women, it was found that their mean height was 63.4 inches. From previous studies, it is assumed that the standard deviation, σ , is 2.4. Construct the 95% confidence interval for the population mean. A) (61.9, 64.9) B) (58.1, 67.3) C) (59.7, 66.5) D) (60.8, 65.4) Page 214
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4) A random sample of 150 students has a grade point average with a mean of 2.86 and with a population standard deviation of 0.78. Construct the confidence interval for the population mean, μ , if c = 0.98. A) (2.71, 3.01) B) (2.51, 3.53) C) (2.43, 3.79) D) (2.31, 3.88) 5) A random sample of 40 students has a mean annual earnings of $3120 and a population standard deviation of $677. Construct the confidence interval for the population mean, μ if c = 0.95.
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This note was uploaded on 06/06/2010 for the course EC 11 taught by Professor All during the Spring '10 term at UCLA.

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ch09 - Ch.9...

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