20. Use the following values from Student’s t-distribution to establish a 95% confidence
interval for the population mean given a sample size of 10, a sample mean of 6.25, and a
sample standard deviation of 12. Assume that the population from which the sample is
drawn is normally distributed and the population variance is not known.
Degrees of freedom p = 0.10 p = 0.05 p = 0.025 p = 0.01
9 1.383 1.833 2.262 2.821
10 1.372 1.812 2.228 2.764
11 1.363 1.796 2.201 2.718
The 95% confidence interval is closest to:
A. a lower bound of -2.33 and an upper bound of 14.83.
B. a lower bound of -2.20 and an upper bound of 14.70.
C. a lower bound of -0.71 and an upper bound of 13.20.
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