The US. Postal Service is concerned with the time it takes to deliver mail. It would like not to only deliver mail as quickly as possible but also to have as little variation as possible. Twenty letters are mailed from New York collection boxes to Cutbank, Montana. Provided below is the number of days that it took each letter to arrive in Cutback, Montana. 3+2=5 a) Calculate all measures of central tendency (mean, median, mode). b) Which one would be the most appropriate measure of central tendency? 1, 5, 3, 4, 3, 2, 6, 1,3, 3, 4, 3, 8, 3, 5, 2, 3,4,4, 3