The average salary of $20$ workers in an office is $Rs. 1900$ per month. If the manager's salary is added,the average becomes $Rs. 2000$ per month. The manager's annual salary (in $Rs.$) is

$A$ batsman has an average of $30$ runs in his $42$ innings. The difference between his maximum and minimum score is $100$. If these two innings are removed,his average for $40$ innings comes down to $28$. What is his minimum score?

The arithmetic mean of $100$ observations is $24$. If $6$ is added to each of the observations and then each of them is multiplied by $2.5$,find the new arithmetic mean.

The average of marks obtained by $150$ candidates in a certain examination is $50$. If the average marks of passed candidates is $55$ and that of the failed candidates is $25$,what is the number of candidates who passed the examination?

In the first $30$ overs of a cricket match,the run rate was $5.2 \text{ runs/over}$. What is the required run rate in the remaining $20$ overs to reach the target of $280$ runs?

The average of the first $n$ consecutive even numbers is $101$. Find their sum.