Direction : The question consists of three statements numbered “I”, "II", and “III” given below it. You have to determine which statement(s) is / are sufficient/ necessary to answer the questions.

What is the average age of a class does 25 students including the age of the headmaster and the class teacher.

Statement I : The ratio of the present age of the class teacher and the headmaster is 11 : 12 and the average age of the class of 25 students excluding the class teacher and the headmaster is 14 years.

Statement II : When two new students of the age of 25 years and the age of the class teacher and the headmaster is not included, the average age of the class is 14.2 years.

Statement III : There is difference of 6 years between the present age of the class teacher and the headmaster.