The arithmetic mean of the first $n$ natural numbers is:

If the values $1, \frac{1}{2}, \frac{1}{3}, \frac{1}{4}, \frac{1}{5}, \dots, \frac{1}{n}$ occur at frequencies $1, 2, 3, 4, 5, \dots, n$ in a distribution,then the mean is

The geometric mean of the numbers $4, 5, 10, 20, 25$ is .........

The median of a set of $9$ distinct observations is $20.5$. If the four largest observations of the set are increased by $2$,what will be the median of the new set?

The mean marks of $100$ students in a class in mathematics is $72$. If the number of boys is $70$ and their mean marks is $75$,find the mean marks of the girls in the class.

Let $x_1, x_2, \ldots, x_{11}$ be $11$ distinct positive integers. If we replace the largest of these integers by the median of the other $10$ integers,then: