Find the mean deviation about the mean for the following data. | Statistics | SciPiPupil

Question: Find the mean deviation about the mean for the following data:

Mark	30-40	40-50	50-60	60-70	70-80	80-90	90-100
Number Of Students	3	7	12	15	8	3	2

Solution:

Arranging data in a table,

Marks	Frequency (f)	Mid Value(x)	fx	|x-x̄|	f|x-x̄|
30-40	3	35	105	27	81
40-50	7	45	315	17	113
50-60	12	55	660	7	84
60-70	15	65	975	3	45
70-80	8	75	600	13	104
80-90	3	85	255	23	69
90-100	2	95	190	33	66
	N= 50		$\sum$fx = 3100		$\sum$f|x-x̄| = 568

Now,

Mean (x̄) =$\dfrac{\sum fx}{N}$

$= \dfrac{3100}{50}$

$= 62$

And,

Mean Deviation from Mean (M.D.) = $\dfrac{\sum f|x-x̄|}{N}$

$= \dfrac{568}{50}$

$= 11.36$

Hence, the required mean deviation about the mean of the given data is 11..36

Related Notes and Solutions:

Here is the website link to the notes of Statistics of Class 10.

#SciPiPupil