Try the following GRE quantitative reasoning question that tests your understanding of the averages (arithmetic mean).
Question#98:
The Dunbar family consists of a mother, a father, and some children. The average age of the members of the family is $20$, the father is $48$ years old, and the average age of the mother and children is $16$. How many children are in the family?

$\quad 2$

$\quad 3$

$\quad 4$

$\quad 5$

$\quad 6$