劉同學(xué)
2018-03-25 15:37Use the following values from a student's t-distribution to establish a 95% confidence interval for the population mean given a sample size of 10, a sample mean of 6.25, and a sample standard deviation of 12. Assume that the population from which the sample is drawn is normally distributed and the population variance is not known. The 95% confidence interval is closest to a: A Lower bound of –2.33 and an upper bound of 14.83. B Lower bound of –0.71 and an upper bound of 13.21. C Lower bound of –2.20 and an upper bound of 14.70. 這題為什么選2.262這個(gè)系數(shù)？為什么選這個(gè)自由度？
所屬：CFA Level I 視頻位置 相關(guān)試題
來(lái)源： 視頻位置 相關(guān)試題
1個(gè)回答
金程教育顧老師助教
2018-03-26 18:12
該回答已被題主采納
學(xué)員你好，因?yàn)榭傮w正態(tài)，小樣本，用t分布，df=樣本量-1=9，查雙尾的t分布表，置信度為95%或顯著性水平為5%那列，得t值為2.262.
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