After the ham is cured, it may be smoked to add flavor or to make sure it lasts longer. Typical grocery-store hams are smoked for the short period of time, while gourmet hams are generally smoked for at least one month. A random sample of 36 grocery-store hams was obtained, and length of smoking time was recorded for each. Mean was =140 hours. Suppose = 8 hours.
Determine 95% confidence interval for mean amount of time grocery-store ham is smoked.