constructing a confidence interval please help

tennisair · #1 $Old$ June 20th, 2009, 05:08 PM

Using the given degree of confidence and sample data to construct a confidence interval for the population mean u. Assume that the population has a normal distribution.
n=10
xbar=8.7
s=3.3
95% confidence

Random Variable · #2 $Old$ June 20th, 2009, 05:40 PM

We the fact that $T = \frac {\bar{X} - \mu}{S / \sqrt{n}}$ follows a t-distribution with n-1 degrees of freedom.

$\bar{x} \ \pm \ t_{(\alpha / 2, n-1)}\Big(\frac{s}{\sqrt{n}}\Big)$

$\Big[8.7 - t_{(0.025, 9)}\Big(\frac{3.3}{\sqrt{10}}\Big), \ 8.7 + t_{(0.025, 9)}\Big(\frac{3.3}{\sqrt{10}}\Big)\Big]$