Testing a Single Mean

The population standard deviation is known.
The standard error of the mean is \(2.5\). You then find the probability of a sample mean more than \(25-20=5\) from the population mean of \(20\). This is the probability outside \(15\) and \(25\) given a distribution with a mean of \(20\) and a standard deviation of \(2.5\). The probability is .0455.
\(2.6693\) Make sure you divide by \(\mathrm{N}-1\).
\(0.9437\) You divide \(s\) by the square root of \(\mathrm{N}\).
You divide \(\mathrm{M}=1.625\) by the standard error of the mean \((.9437)\) to get \(1.72\).
You use \(N-1=7\) degrees of freedom. \(p=.1288\)
\(t=1.4626\)
\(t=-0.7917\)
\(p=0.8319\)