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 consecutive numbers is $n .$ If the next two consecutive numbers are also included, the average of the five numbers will
The arithmetic mean of $100$ observations is $24.6$ is added to each of the observations and, then each of them is multiplied by $2.5 .$ Find the new arithmetic mean.
The average weight of $36$ students is $50 \,kg$. If was found later that the weight of one of the student was misread as $73 \,kg$. whereas his actual weight was $37 \,kg$. Find the correct average. (in $kg$)
The average weight of $4$ men $A, B, C$ and $D,$ is $67\, kg.$ The $5^{th}$ man $E$ is included and the average weight decreases by $2 \,kg$. A is replaced by $F.$ The weight of $F$ is $4 \,kg$ more than $E$. Average weight deereases because of the replacement of $A$ and now the average weight is $64\, kg.$ Find the weight of $A ?$
In an entrance examination, Ritu scored $56$ percent marks, Smita scored $92$ percent marks and Rina scored $634$ marks. The maximum marks of the examination is $875 .$ What is the average marks scored by all the three girls together ?