Out of nine persons,$8$ persons spent $Rs. 30$ each for their meals. The ninth person spent $Rs. 20$ more than the average expenditure of all the nine. What was the total money spent by all of them (in $Rs.$)?

The average expenditure of a man for the first five months is $Rs. 120$ and for the next seven months is $Rs. 130$. His monthly average income in $Rs.$ if he saves $Rs. 290$ in that year,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 $\text{years}$)?

If the mean of $5$ observations $x, x+2, x+4, x+6$ and $x+8$ is $11,$ then the mean of the last three observations is

The average age of a group of persons going for a picnic is $16.75 \text{ years}$. $20$ new persons with an average age of $13.25 \text{ years}$ join the group on the spot,due to which the average age of the group becomes $15 \text{ years}$. Find the number of persons initially going for the picnic.

$16$ children are to be divided into two groups $A$ and $B$ of $10$ and $6$ children,respectively. The average marks obtained by the children of group $A$ is $75$ and that of all the children is $76$. Then,the average marks of the children of group $B$ is?