The average age of a class of 40 students is 18 years. When a teacher joins them, their average age becomes 19 years. Find the teachers age.

The average age of a class of 35 students is 15 years. If the teacher's age is also included the average age Increases by one year. Furthermore, if the average age of the teacher's family having a wife and a son is 40 years and the son's age in 80% less than his-mother's age, then the age of the teacher's wife is

The average age of a class of 39 students is 15 years.If the age of the teacher be included, then the average increases by 3 months.Find the age of the teacher.

The average age of a class is 21 years. If a student with age 42 years joins the class, then new average age becomes 24 years. How many total students are there in the class?

Average age of 10 students of a class is 18 years. If one more student join them now , the average becomes 19 years .What is the age of new student ?