The raw scores of 20 students of a school who took part of an examination in Economics are given below; 38, 39, 12, 20, 18, 28, 20, 46, 34, 20, 70, 64, 52, 48, 64, 43, 66, 53, 69, 34. a) What is the mean score of the students' marks b) How many students passed the exam c) What percentage of the students failed the exam d) What is the range of the scores e) Calculate the mean deviation