What will be the average of even numbers between $11$ and $63$?

The average age of four brothers is $12 \, \text{years}$. If the age of their mother is also included, the average increases by $5 \, \text{years}$. The age of the mother (in $\text{years}$) is:

The bowling average of a cricketer was $12.4$. He improves his bowling average by $0.2$ points when he takes $5$ wickets for $26$ runs in his last match. The number of wickets taken by him before the last match was?

The average weight of $25$ persons is increased by $1 \, kg$ when one man weighing $60 \, kg$ is replaced by a new person. What is the weight of the new person (in $kg$)?

The average of $12$ results is $15,$ and the average of the first two is $14.$ What is the average of the rest?

The average age of a family of $6$ members $4$ years ago was $25$ years. Meanwhile,a child was born in this family,and the average age of the whole family is still the same today. The present age of the child in years is?