The average of the squares of of first ten natural numbers is
$35.5$
$36$
$37.5$
$38.5$
A cricketer has a certain average for $10$ innings. In the eleventh inning, he scored $108$ runs, thereby increasing his average by $6$ runs. His new average is
The average marks of a student obtained in Physics, Chemistry and Biology is $70.$ If the student obtained $90\, marks$ in Mathematics, then the new average is
A cyclist goes from a place to another and returns by the same route. He pedals his way uniformly with speed $u$ while going and with speed $v$ while returning. The average speed of his journey is
There are two groups $A$ and $B$ of a class, consisting of $42$ and $28$ students, respectively. If the average weight of group $A$ is $25 \,kg$ and that of group $B$ is $40 \,kg ,$ find the average weight of the whole class.
The sum of the ages of father and son at present is $33\,years.$ Two years ago the product of their ages was $28 \,years.$ What is the age of the father and the son? (in $years$)