PracticeQuestions7

# PracticeQuestions7 - Practice Questions 7 1 You are...

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Practice Questions 7 1. You are interested in examining the salaries earned by graduate business school students at the end of the first year after graduation. In particular, you are interested in seeing whether there is a difference between men and women graduates’ salaries. From a random sample of 55 women, you find the mean salary to be \$47,520 with a standard deviation of \$5,633. From a sample of 64 men, you find the mean salary to be \$44,304 with a standard deviation of \$4,793. What is the 95% confidence interval for the difference between the population mean salary for men and women? Assume the random sample observations are from normally distributed populations, and that the population variances are assumed to be equal. A) \$3,216 r 0.05 955 z t B) \$3,216 r 117,0.05 955 t t C) \$3,216 r 0.025 955 z t D) \$3,216 r 117,0.025 955 t t 2. In a recent survey of 240 teachers in Richmond, Virginia, 77.2% supported standardized national testing of elementary students. In a survey of 162 teachers in Raleigh, North Carolina, 64.2% supported national testing. Find a 99% confidence interval for the difference between the two population proportions. A) 0.13 r 0.119 B) 0.13 r 0.092 C) 0.13 r 0.135 D) 0.13 r 0.148 3. You are interested in determining the average cost of a 3-minute telephone call to locations within the continental U.S. What sample size must you take to be 96% confident that the results will be within \$.75 of the true mean cost per call given that 7.71 σ = ? A) 185 B) 445 C) 406 D) 574 4. Because of the popularity of movies as an entertainment medium for college students, you plan to do a national study of the average cost of a movie ticket. If you assume that = \$0.50, what sample size would you have to take to be 95% confident that your estimate was within \$0.25 of the true mean ticket prices? A) 15 B) 7 C) 16 D) 8 5. The Arkansas State Police wish to estimate the average mph being traveled on the Interstate Highways, which cross the state. If the estimate is to be within 8 mpg of the true mean with 98% confidence and the population standard deviation is 22 mph, how large a sample size must be taken? A) 42 B) 15

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C) 329 D) 14 6. The pooled variance 2 p s is formed by combining information from two independent samples. If 2 1 s =39, 2 2 s = 25, and 1 2 , n n = then 2 p s is A) 64 B) 8 C) 32 D) 14 7. If we wish to construct a 95% confidence interval estimate for the difference between two population proportions, then the confidence level would be A) 1.96 B) 0.95 C) 0.475 D) 0.05 8. In constructing 95% confidence interval estimate for the difference between the means of two normally distributed populations, where the unknown population variances are assumed not to be equal, summary statistics computed from two independent samples are as follows: 50 1 = n , 175 1 = x , 5 . 18 1 = s , 42 2 = n , 158 2 = x , and 4 . 32 2 = s . The upper confidence limit is: A) 19.123 B) 28.212 C) 24.911 D) 5.788 9. A researcher is interested in determining the proportion of college students who have
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PracticeQuestions7 - Practice Questions 7 1 You are...

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