Problem 7-38 The average active-ingredient yield per liter of raw material for samples of vials may be approximated by a normal distribution with mean 23 grams and standard deviation 0.2 grams. (a) Find: (1) Pr[average yield of a sample is less than 22.6 grams] = (2) Pr[average yield of a sample is between 22.6 and 23.4 grams] = (3) Pr[average yield of a sample is greater than 23.4 grams] = (b) Find the following percentiles: (1) 10th percentile = (2) 20th percentile = (3) 90th percentile = (4) 99th percentile =