The average of the price per $kg$ of rice at $10$ different places was $Rs.\, 4.85.$ After a week, the price per $kg.$ was increased by $20$ paise at $3$ places and decreased by $10$ paise at one place. The new average of price per $kg$ is in $Rs.$

The average age of $x$ and $y$ is $20$ $years.$ If $z$ were to replace $x,$ the average would be $19$ and if $z$ were to replace $y$, the average would be $21.$ Find the ages of $x, y$ and $z$.

A cricketer whose bowling average is $12.4$ runs per wicket takes $5$ wickets for $26$ runs and thereby decreases his average by $0.4$ The number of wickets taken by him till the last match was

The average marks of $120$ students are $35.$ If average of passed students was $39$ and failed students was $15,$ then Find the number of students who have passed?

There was one mess for $30$ boarders in a certain hostel. On the number of boarders being increased by $10,$ the expenses of the mess were increased by $Rs.\,40$ per month while the average expenditure per head diminished by $Rs.\,2.$ Find out actual monthly expenses. (in $Rs.$)

The average expenditure of a man for the first five months is $Rs.\, 120$ and for the next seven months is $Rs. \,130$ . His monthly average income in $Rs.$ if he saves $Rs. \,290$ in that year, is