x_i 5 7 9 10 12 15 f_i 8 6 2 2 2 6 - NCERT Class XI Mathematics ...

NCERT Class XI Mathematics - Statistics - Solutions

Question : 7 of 34

Marks: +1, -0

$x_i$	5	7	9	10	12	15
$f_i$	8	6	2	2	2	6

Solution:

$x_i$	$f_i$	c.f.	$\left\|x_i-7\right\|$	$f_i\left\|x_i-7\right\|$
5	8	8	2	16
7	6	14	0	0
9	2	16	2	4
10	2	18	3	6
12	2	20	5	10
15	6	26	8	48
	26			84

Here,

\frac{N}{2}

\frac{26}{2}

= 13

The c.f. just greater than 13 is 14 and the corresponding value of x is 7.

So, Median (M) = 7

∴ M.D. about median =

\frac{1}{N}\sum_{i=1}^{n}f_i\left|x_i-M\right|

\frac{1}{26}

× 84 = 3.23

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