For a normal distribution,which of the following relations holds true?

The mode of the following frequency distribution is:

Class	$0-5$	$5-10$	$10-15$	$15-20$	$20-25$	$25-30$
Frequency $(f_i)$	$3$	$4$	$7$	$11$	$2$	$5$

If $\alpha, \beta, \gamma$ are the mean deviations about the mean,median,and mode of the data $1, 2, 2, 3, 3, 3, 4, 6$ respectively,then

For a discrete series (where all values are not equal),what is the relationship between Mean Deviation $(M.D.)$,Mean $(Mean)$,and Standard Deviation $(S.D.)$?

In a frequency distribution,if the mean and median are $21$ and $22$ respectively,then what is the approximate mode?

If $\text{Mean} = x(3 \times \text{Median} - \text{Mode})$,then what is the value of $x$?