NCERT Class XI Mathematics - Statistics - Solutions | Question 16

NCERT Class XI Mathematics - Statistics - Solutions

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Question : 16

Total: 34

xi	6	10	14	18	24	28	30
fi	2	4	7	12	8	4	3

Solution:

xi	fi	fixi	(xi−19)	(xi−19)2	fi(xi−19)2
6	2	12	- 13	169	338
10	4	40	- 9	81	324
14	7	98	- 5	25	175
18	12	216	-1	1	12
24	8	192	5	25	200
28	4	112	9	81	324
30	3	90	11	121	363
	40	760			1736

Mean (

−

x

) =

1

N

n

Σ

i=1

fixi =

1

40

× 760 = 19
Variance (σ2) =

1

N

n

Σ

i=1

fi(xi−

−

x

)2 =

1

40

× 1736 = 43.4

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