9. Drums are made in a factory. The diameters of the drums made are normally distributed and have a mean of 18.2 in and a standard deviation of 2.0. (a) Find the percentage of drums that are less than 18.5 inches in diameter. (first state the normal distribution z value corresponding to 18.5) (show work for the z calculation) Z= P = (b) If 36 drums are randomly chosen, find the probability their mean diameter is less than 18.5 inches. (first state the sampling distribution z value corresponding to 18.5) (show work for the z calculation) Z= P =