The mean of $19$ observations is $4$. If one more observation of $24$ is added to the data,the new mean will be

$A$ family consists of grandparents,parents,and three grandchildren. The average age of the grandparents is $67 \text{ years}$,that of the parents is $35 \text{ years}$,and that of the grandchildren is $6 \text{ years}$. What is the average age of the family? (in $\text{years}$)

$16$ children are to be divided into two groups $A$ and $B$ of $10$ and $6$ children. The average percent marks obtained by the children of group $A$ is $75$ and the average percent marks of all the $16$ children is $76$. What is the average percent marks of children of group $B$?

The sum of the ages of father and son at present is $33 \, \text{years}$. Two years ago, the product of their ages was $28 \, \text{years}$. What is the age of the father and the son (in $\text{years}$)?

The average of the first $46$ natural numbers is:

The average age of mother,father,and son was $42$ years at the time of the son's marriage. After one year,an infant was born in the family,and after $6$ years of marriage,the average age of the family is $36$ years. What was the age of the bride at the time of marriage in years?