Sachin Tendulkar has a certain average for $11$ innings. In the $12^{th}$ innings he scores $120$ runs and thereby increases his average by $5$ runs. His new average is

The average age of the boys in a class is $16 \text{ years}$ and that of the girls is $15 \text{ years}$. The average age for the whole class is:

The average monthly salary of all the employees in an industry is $Rs. 12,000$. The average salary of male employees is $Rs. 15,000$ and that of female employees is $Rs. 8,000$. What is the ratio of male employees to female employees?

There are $6$ consecutive odd numbers in increasing order. The difference between the average of the squares of the first $4$ numbers and the last $4$ numbers is $64$. If the sum of the squares of the first and the last element is $178$,then the average of all the $6$ numbers is:

Ashish has earned an average of $4200$ dollars for the first eleven months of the year. If he justifies his staying on in the $US$ on the basis of his ability to earn at least $5000$ dollars per month for the entire year,how much should he earn (in dollars) in the last month to achieve his required average for the whole year?

$A$ group of boys has an average weight of $36 \,kg$. One boy weighing $42 \,kg$ leaves the group and another boy weighing $30 \,kg$ joins the group. If the average now becomes $35.7 \,kg$,then how many boys are there in the group?