Asked Dec 1, 2019
  1. A retirement community takes a random sample of 25 of its residents and finds the average age is 74. The sample standard deviation is 9.8 years. Calculate a 99% confidence interval for the mean. Round to one decimal place.

Expert Answer

Step 1


From the given information, the sample mean is 74, the sample standard deviation is 9.8 and the sample size is 25. Here, the sample size is less than 30 and the population standard deviation is known. Hence, the suitable test is t test.


The sample size is n=25 and the confidence level is 99%.

The degree of freedom is, ...

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