A student finds the average of $10,2$ digit numbers. If the digits of one of the number is interchanged, the average increases by $3.6 .$ The difference between the digits of the $2 -$digit numbers is
$4$
$3$
$2$
$5$
A librarian purchased $50$ $story-books$ for his library. But he saw that he could get $14$ more books by spending $Rs.\, 76$ more and average price per book would be reduced by $Rs.\,1.$ The average price (in $Rs.$) of each book he bought, was
The average salary of $15$ persons is $Rs.\, 5,500.$ If the salary of one person is added, the average increase to $Rs. \,5,700 .$ What is the salary of this one person in $Rs. \, ?$
The average annual income (in $Rs.$) of certain agricultural workers is $S$ and that of other workers is $T$. The number of agricultural workers is $11$ times that of other workers. Then the average annual income (in $Rs.$) of all the workers is
The average of runs of a cricket player of $10$ innings was $32 .$ How many runs must he score in his next innings so as to increase his average of runs by $4 ?$
The average weight of five persons sitting in a boat is $38\, kg.$ The average weight of the boat and the persons sitting in the boat is $52\, kg.$ What is the weight of the boat (in $kg$)?