1. The average age of a class of 39 students is 15 years. If the age of the teacher is included, then the average increases by 3 months. Find the age of the teacher.
4. The ratio of the present ages of Aman and Ankit is 2 : 1 and the sum of their present ages is 72 years. What will be the Aman's age (in years) after 6 years?
5. The average age of a class of 6 girls is x years. Four new girls having ages x ? 2, x + 2, x + 4 and x + 6 joins the class. What is the new average age (in years) of the class?
6. The age of Dr. Pandey is four times the age of his son. After 10 years , the age of Dr. Pandey will be twice the age of his son . The present age of Dr. Pandey's son is
7. Three years ago, the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today. The present age of the baby is
8. The ratio of ages of the father and mother was 11:10 when their son was born. The ratio of ages of the father and mother will be 19:18 when the son will be twice his present age. What is the ratio of present ages of father and mother?
10. The ratio of present ages of Rahul and his sister is 3 : 4. Before 10 years the ratio of their ages was 13:19. What is Rahul's present age (in years)?