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

The relation between the median $M$,the second quartile ${Q_2}$,the fifth decile ${D_5}$,and the $50^{th}$ percentile ${P_{50}}$ of a set of observations is:

The arithmetic mean of a set of observations is $\overline{X}$. If each observation is divided by $\alpha$ and then increased by $10$,then the mean of the new series is

The mean of a set of numbers is $\bar x$. If $\lambda$ is subtracted from each number,what will be the mean of the new set?

If for some $x \in R$,the frequency distribution of the marks obtained by $20$ students in a test is:
Marks: $2, 3, 5, 7$
Frequency: $(x+1)^2, 2x-5, x^2-3x, x$
Then the mean of the marks is:

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