A recent study of long distance phone calls made from WPU, showed that the length of the calls follows the normal probability distribution with a mean of 3.2 minutes per call and a standard deviation of 0.50 minutes. (a) What fraction of the calls last between 3.2 and 4 minutes? (b) What fraction of the calls last more than 4 minutes? (c) What fraction of the calls last between 4 and 4.5 minutes? (d) What fraction of the calls last between 3 and 4.5 minutes?