The average of the first $100$ positive integers is

$10 \, kg$ of rice priced at $Rs. \, 12$ per $kg$ is mixed with $6 \, kg$ of rice priced at $Rs. \, 16$ per $kg$. Find the average price in $Rs.$ per $kg$ of the whole mixture?

The average of $6$ observations is $12$. $A$ new seventh observation is included and the new average is decreased by $1$. The seventh observation is

In a $20$ over match,the required run rate to win is $7.2$. If the run rate is $6$ at the end of the $15^{th}$ over,the required run rate to win the match is

Of the three numbers,the average of the first and the second is greater than the average of the second and the third by $15$. What is the difference between the first and the third of the three numbers?

The average salary of all the staff in an office of a corporate house is $Rs. 5,000$. The average salary of the officers is $Rs. 14,000$ and that of the rest is $Rs. 4,000$. If the total number of staff is $500$,what is the number of officers?