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The proprieter of a boutique in New York wanted to determine the average age of his...


The proprieter of a boutique in New York wanted to determine the average age of his customers. A random sample of 25 customers revealed an average of 28 years with a standard deviation of 10 years. Determine a 95% confidence interval estimate for the average age of all his customers.
Math   Statistics-And-Probability   
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Answer #1

GIVEN:

Sample size

Sample mean

Sample standard deviation

FORMULA:

The formula for 95% confidence interval for population mean is,

where is the two sided t critical value with degrees of freedom at significance level

CRITICAL VALUE:

The two sided t critical value with degrees of freedom at significance level is .

CALCULATION:

The 95% confidence interval estimate for the average age of all customers of boutique in New York is given by,

  

The 95% confidence interval estimate for the average age of all his customers is . Thus we are 95% confident that the interval captured the true mean age of all customers of boutique in New York.

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