Suppose the data have a bell-shaped distribution with a mean of 30 and a standard deviation of 5. Use the empirical rule to determine the percentage of data within each of the following ranges. (a) 20 to 40 approximately 68% approximately 95% almost all (b) 15 to 45 approximately 68% approximately 95% almost all (c) 25 to 35 approximately 68% approximately 95% almost all