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標題:
statistic 問題
發問:
from a populartion of 5000 invoices, a simple random sample of 144 was selectes. the arithmetic mean value per invoice was $210 with a standard deviation of $24. find the 95% confidence interval for the population mean. 個mean係210, 噤點搵z table?
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最佳解答:
n=144, X_bar=210, s.d.=24 confidence interval for mean: X_bar +/- (critical value)*[s.d./sqrt(n)] critical value depends on the significance level, in this case significance level alpha=0.05, so the critical value will be Z(alpha/2), which is 1.96. mu falls in 210 +/- 1.96[24/sqrt(144)] = 210 +/- 3.92 confidence interval for mean (mu)=[206.08, 213.92]
其他解答:A9A3995907B431A4
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