If the mean of $5$ observation $x, x+2, x+4, x+6$ and $x+8$ is $11,$ then the mean of the last three observations is
$11$
$13$
$15$
$17$
If the average of $x$ and $\frac{1}{x}(x \neq 0)$ is $M,$ then the average of $x^{2}$ and $\frac{1}{x^{2}}$ is
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
The average age of $20$ boys in the class is $15.6\, years.$ Five new boys join and the new average becomes $15.56\, years.$ What is the average age of the five new boys? (in $years$)
The average of $7$ consecutive numbers is $20 .$ The largest of these numbers is
The average weight of $10$ students is increased by half a $kg$ when one of the students weighing $50\, kg$ is replaced by a new student. Find out the weight of the new student.(in $kg$)