(3) Using the parameters for a standard normal distribution, complete parts (a) - (d). (a) What percent of z-scores are less than 2.5? (b) What z-scores separate the usual 95% of data from the unusual 5% of data that falls in both tails of the distribution? (c) Using the empirical rule, what z-scores separate the usual from the unusual? (d) Compare the results in parts (b) and (c). Do the two methods result in the same solution