Spring09Midterm1A

# Spring09Midterm1A - Midterm 1 Form A Spring 2009 Economics...

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2. An electrical contractor has observed that his accounts are paid on average in 40 days, with a standard deviation of 10 days. Using the empirical rule, estimate what proportion of the accounts will be paid between 50 and 60 days? a. 5% b. 13.5% c. 27% d. 68% e. 95% 3. Which of the following statements is false ? a. the median is greater than the mode when a distribution is skewed to the right. b. the median of a distribution that is symmetric is equal to the mean. c. the median is less than the mean when a distribution is skewed to the right. d. the median value is the middle value in a dataset. e. the median is the most commonly observed value. Use the following information to answer the next 3 questions (4-6): A meteorologist is interested in determining if the variance of temperatures is diﬀerent be- tween Boston and New York . She randomly samples 60 days over a 40 year period for Boston and another random 50 days over the same period for New York. The sample variance for Boston (population 1) is found to be 8.6 and the sample variance for New York (population 2) is found to be 12.7. 4. What are the appropriate null and alternative hypotheses for the meteorlogist’s question? a. H 0 : σ 2 1 - σ 2 2 = 1 vs. H 1 : σ 2 1 - σ 2 2 6 = 1 b. H 0 : σ 2 1 σ 2 2 > 0 vs. H 1 : σ 2 1 σ 2 2 < 0 c. H 0 : σ 2 1 σ 2 2 = 1 vs. H 1 : σ 2 1 σ 2 2 > 1 d. H 0 : σ 2 1 σ 2 2 = 1 vs. H 1 : σ 2 1 σ 2 2 6 = 1 e. H 0 : σ 2 1 σ 2 2 > 1 vs. H 1 : σ 2 1 σ 2 2 < 1 2
5. What is the value of the appropriate test statistic?

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Spring09Midterm1A - Midterm 1 Form A Spring 2009 Economics...

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