Find the average of first $25$ multiples of $5 .$
$65$
$60$
$75$
$80$
A car owner buys petrol at $Rs.\,7.50, Rs.\, 8$ and $Rs.\, 8.50$ per $litre$ for three successive years. What approximately is the average cost per litre of petrol if he spends $Rs.\, 4000$ each year ?(in $Rs.$ )
A batsman makes a score of $8$ runs in the $16^{\text {th }}$ match and thus increases his average runs per match by $3 .$ What is his average after the $16^{\text {th }}$ match?
The average age of a family of $6$ members is $22\, years.$ If the age of the youngest member be $7\, years,$ then what was the average age of the family at the birth of the youngest member?
The average salary per head of all workers of an institution is $Rs. \,60\,.$ The average salary per head of $12$ officers is $Rs. \,400 .$ The average salary per head of the rest is $Rs.$ $56 .$ Then, the total number of workers in the institution is?
The average daily wages of $A, B$ and $C$ is $Rs.\, 120 .$ If $B$ earns $Rs.\,40$ more than $C$ per $day$ and $A$ earns double of what $C$ earns per $day,$ the wages of $A$ per $day$ is (in $Rs.$)