As reported in Runner's World magazine, the times of the finishers in the New York City 10-km run are normally distributed with mean 61 minutes and standard deviation 9 minutes. a. Determine the percentage of finishers who have times between 55 and 75 minutes. b. Obtain and interpret the 60th percentile for the finishing times. c. Find the middle 40% of the finishing times. d. Extra credit: If a random sample of 10 Runner's are selected find the probability that their mean finishing time is between 55 and 75 minutes