Five years ago the average age of husband and wife was $23\, years.$ Today the average age of husband, wife and child is $20 \,years.$ How old is child in $years$ ?
$3$
$4$
$12$
$2$
The average of five numbers is $6.9 .$ If one of the numbers is deleted, the average of the remaining numbers is $4.4 .$ What is the value of the number deleted?
The average marks obtained by a class of $60$ students is $05.$ The average marks of half of the students is found to be $85 .$ The average marks of the remaining students is
Average of ten numbers is calculated. If each number was increased by $12 \%$, then the average
$16$ children are to be divided into two groups $A$ and $B$ of $10$ and $6$ children, respectively. The average marks obtained by the children of group $A$ is $75$ and that of all the children is $76 .$ Then, the average marks of the children of group $B$ is ?
The average marks of students in an examination was $65 .$ It was later found that the marks of one students had been wrongly entered as $83$ instead of $38.$ the correct average is ?