The mean daily profit made by a shopkeeper,in a month of $30$ days,was $Rs. 350$. If the mean profit for the first $15$ days was $Rs. 275$,then the mean profit for the last $15$ days would be (in $Rs.$)

The average weight of $4$ men $A, B, C,$ and $D$ is $67 \, kg.$ When a $5^{th}$ man $E$ is included,the average weight decreases by $2 \, kg.$ $A$ is replaced by $F.$ The weight of $F$ is $4 \, kg$ more than $E.$ The average weight decreases because of the replacement of $A,$ and now the average weight is $64 \, kg.$ Find the weight of $A.$

In a competitive examination,the average marks obtained was $45$. It was later discovered that there was some error in computerization and the marks of $90$ candidates had to be changed from $80$ to $50$,and the average came down to $40$ marks. The total number of candidates appeared in the examination is

The average of ten numbers is calculated. If each number is increased by $12 \%$,then the average

The average age of $8$ members of a group is $40 \text{ years}$. The age of $1$ member is $55 \text{ years}$. After his retirement,a new member of age $39 \text{ years}$ joins the group. What is the effect of this replacement on the average age of the group?

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