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A random sample of 90 observations produced a mean x?=
Chapter 6, Problem 4E(choose chapter or problem)
Problem 4E
A random sample of 90 observations produced a mean x̄= 25.9 and a standard deviation s= 2.7.
a. Find an approximate 95% confidence interval for the population mean μ.
b. Find an approximate 90% confidence interval for μ.
c. Find an approximate 99% confidence interval for μ.
Questions & Answers
QUESTION:
Problem 4E
A random sample of 90 observations produced a mean x̄= 25.9 and a standard deviation s= 2.7.
a. Find an approximate 95% confidence interval for the population mean μ.
b. Find an approximate 90% confidence interval for μ.
c. Find an approximate 99% confidence interval for μ.
ANSWER:
Answer:
Step 1 of 3:
Given,
a). To find an approximate 95% confidence interval for the population mean
For confidence coefficient 0.95, and
(using the standard normal table, the z value for 95% CI is 1.96)
That is,
The confidence interval is
(25.34, 26.46)
Therefore, the confidence interval is (25.34, 26.46).