The average age of $30$ women decreases by $3$ months if a new person,Neha,is included in place of a $25$ year old woman. Calculate the age of Neha in years.

$A$ cricketer has a certain average for $10$ innings. In the eleventh inning,he scored $108$ runs,thereby increasing his average by $6$ runs. His new average is

The average age of $36$ students in a group is $14$ years. When the teacher's age is included, the average increases by $1$. What is the teacher's age in years?

The average age of a committee of $8$ members is $40 \text{ years}$. $A$ member,aged $55 \text{ years}$,retired and was replaced by a member aged $39 \text{ years}$. The average age of the present committee is (in $\text{years}$):

There were $35$ students in a hostel. If the number of students is increased by $7$,the expenditure on food increases by $Rs. \,42$ per day,while the average expenditure per student is reduced by $Rs. \,1$. What was the initial total expenditure on food per day? (in $Rs.$)

Out of four numbers,the average of the first three is $16$ and that of the last three is $15$. If the last number is $20$,then the first number is: