The marks obtained by 110 students in an examination are given below:
Marks : 30 – 35, 35 – 40, 40 – 45, 45 – 50, 50 – 55, 55 – 60, 60 – 65
Frequency : 14, 16, 28, 23, 18, 8, 3

Find the mean marks of the students using assumed mean method.