320_hw8_ans

320_hw8_ans - Economic Statistics: Homework 8 (Estimation)...

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Economic Statistics: Homework 8 (Estimation) Interval Estimation of Population Mean: Variance Known 1. A random sample of sixteen observations from a normal population with standard deviation of 6 had mean 25. Find a 90% confidence interval for the population mean, μ. n = 16, σ = 6, X = 25, 1 - α = 0.90 Since the population is normal, we can use Z since σ is known SMPER = n Z / 2 / σ α = 1.645 (6 / √16) = 2.4675 Interval: 25 +/- 2.4675; 22.5 to 27.5 2. A process produces bags of refined sugar. The weights of these bags are normally distributed with standard deviation 1.2 ounces. The contents of a random sample of twenty five bags had mean weight 19.8 ounces. Find a 95% confidence interval estimate of the true mean weight (population) for all bags of sugar produced by the process. Population is normal, σ known, we use Z. n = 25, σ = 1.2, X = 19.8, 1 - α = 0.95 SMPER = n Z / 2 / = 1.96 (1.2 / √25) = 0.4704 Interval: 19.8 +/- 0.47; 19.33 to 20.27 Interval Estimation of Population Mean: Variance Unknown
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This homework help was uploaded on 04/22/2008 for the course ECON 320 taught by Professor Martin during the Spring '08 term at Allegheny.

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320_hw8_ans - Economic Statistics: Homework 8 (Estimation)...

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