Amitabh's average expenditure from $January$ to $June$ is $Rs. 4200$. He spends $Rs. 1200$ in $January$ and $Rs. 1500$ in $July$. What is the average expenditure for the months of $February$ to $July$ (in $Rs.$)?

The average of nine numbers is $50$. The average of the first five numbers is $54$ and that of the last three numbers is $52$. Then the sixth number is?

After replacing an old member with a new member,it was found that the average age of five members of a club is the same as it was $3 \, \text{years}$ ago. What is the difference between the ages of the replaced member and the new member (in $\text{years}$)?

$12 \%$ of Kaushal's monthly salary is equal to $16 \%$ of Nandini's monthly salary. Suresh's monthly salary is half that of Nandini's monthly salary. If Suresh's annual salary is $Rs.\, 1.08$ lakhs,what is Kaushal's monthly salary in $Rs.$?

The average temperature from Monday to Wednesday is $37^{\circ}C$,while the average temperature from Tuesday to Thursday is $34^{\circ}C$. The temperature of Thursday is $\frac{4}{5}$ times that of Monday. Find the temperature of Thursday in $^{\circ}C$.

The average of $10$ numbers is $7$. What will be the new average if each of the numbers is multiplied by $8$?