The median of $21$ observations is $40$. If each observation greater than the median is increased by $6$,what will be the new median of the observations?

The number of observations in a group is $40$. If the average of the first $10$ observations is $4.5$ and the average of the remaining $30$ observations is $3.5$,then the average of the whole group is:

$A$ school has four sections of chemistry in class $XII$ having $40, 35, 45$ and $42$ students. The mean marks obtained in chemistry test are $50, 60, 55$ and $45$ respectively for the four sections. The overall average of marks per student is:

The mean of the series $a, a + nd, a + 2nd$ is

Find the median of the sequence $^{2n}C_0, ^{2n}C_1, ^{2n}C_2, \dots, ^{2n}C_n$ (where $n$ is even).

What is the weighted mean of the first $n$ natural numbers if the weights are equal?