Solve the problem.
A random sample of n measurements was selected from a population with unknown mean $\mu$ and known standard deviation $\sigma$. Calculate a 90% confidence interval for $\mu$ for the given situation. Round to the nearest hundredth when necessary.
n = 80, $\bar{x}$ = 65, $\sigma$ = 20
65 $\pm$ 3.68
65 $\pm$ 0.49
65 $\pm$ 39.2
65 $\pm$ 4.38