The median of a set of $19$ observations is $30$. If two observations with values $8$ and $32$ are added,what is the median of the new set of $21$ observations?

The median of $10, 14, 11, 9, 8, 12, 6$ is

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.

In a class of $100$ students,there are $70$ boys whose average marks in a subject are $75$. If the average marks of the complete class are $72$,then what are the average marks of the girls?

The mean weight per student in a group of seven students is $55 \ kg$. If the individual weights of $6$ students are $52, 58, 55, 53, 56$ and $54 \ kg$,then the weight of the seventh student is.....$kg$.

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