The average age of a husband and wife was 23 years when they were married 5 years ago. The average age of the husband, wife and a child who was born during the interval is 20 years now. How old is the child now?
The average age of students of class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ratio of number of boys to the number of girls in the class is
Suppose the number of boys and girls are x and y respectively