The marks obtained by 40 students of class IX in an examination are given below:
18, 8, 12, 6, 8, 16, 12, 5, 23, 2, 16, 23, 2, 10, 20, 12, 9, 7, 6, 5, 13, 21, 13, 15, 20, 24, 1, 7, 21, 16, 13, 18, 23, 7, 3, 18, 17, 16.
Present the data in the form of a frequency distribution using the same class size, one such class being 15 – 20 (where 20 is not included).