The average of the first $25$ numbers is $10$ and the average of the next $25$ numbers is $12$. The average of all $50$ numbers is:

The average weight of $45$ students in a class was calculated as $36 \, kg$. It was later found that the weight of two students in the class was wrongly calculated. The actual weight of one of the boys in the class was $32 \, kg$,but it was calculated as $34 \, kg$,and the weight of another boy in the class was $45 \, kg$,whereas it was calculated as $40 \, kg$. What is the actual average weight of the $45$ students in the class? (in $kg$) (Rounded off to two digits after decimal)

The mean weight of $34$ students of a school is $42 \, kg$. If the weight of the teacher is included,the mean weight increases by $400 \, g$. Find the weight of the teacher (in $kg$).

In a family,the average age of father and mother is $38 \text{ years}$,whereas the average age of father,mother,and their only daughter is $28 \text{ years}$. Then,the age of the daughter is? (in $\text{years}$)

The average weight of $A, B$ and $C$ is $45\, kg$. If the average weight of $A$ and $B$ is $40\, kg$ and that of $B$ and $C$ is $43\, kg$,then the weight of $B$ is (in $, kg$)

The average marks of $40$ students in an examination was $25$. It was later found that the marks of one student had been wrongly entered as $73$ instead of $37$. What is the value of the correct average?