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標題:
Statistics 十萭火急 敬請高人幫忙 謝謝 (2)
發問:
Consider a population having a standard deviation equal to 10. We wish to estimate the mean of this population. a) How large a random sample is needed to construct a 95.44 percent confidence interval for the mean of this population with a margin of error equal to 1? 更新: b) Suppose that we now take a random sample of the size we have determined in part a. If we obtain a sample mean equal to 295, calculate the 95.44 percent confidence interval for the population mean. What is the interval's margin of error?
最佳解答:
For a 95.44% confidence interval, we have Z = 2 where Z is the no. of standard deviations. By formula: Z = (X - μ)/(σ/√n) With X - μ = 1 which is the margin of error, we have: 2 = 1/(10/√n) √n = 20 n = 400 So a rendom sample size of 400 is needed. (b) The 95.44% confidence interval is given by: X 2σ/√n = 295 1 So the interval is between 294 and 296.
其他解答:6CC7293C79127CE5
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