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A statistics practitioner took a random sample of 40 observations from a population whose standard deviation...

A statistics practitioner took a random sample of 40 observations from a population whose standard deviation is 15 and compute the sample mean to be 50. The 90% confidence interval for the mean will be between __________ and __________.

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Answer #1

Solution :

Given that,

t /2,df = 1.685

Margin of error = E = t/2,df * (s /n)

= 1.685 * (15 / 40)

Margin of error = E = 4.00

The 90% confidence interval estimate of the population mean is,

- E < < + E

50 - 4.00 < < 50 + 4.00

46 < < 54

The 90% confidence interval for the mean will be between 46 and 54

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