Calculate mean,variance,standard deviation for the following distribution
Classes- 30-40 40-50 50-60 60-70 70-80 80-90 90-100
frequency 3 7 12 15 8 3 2

Question

​​Calculate mean,variance,standard deviation for the
following distribution
​Classes- 30-40 40-50 50-60 60-70 70-80 80-90 90-100
frequency 3 7 12 15 8 3 2

Aarushi Mishra · Accepted Answer

Classes
Class mark xi
frequency fi
xifi

xi-x
xi-x2

30-40
35
3
105
27
729

40-50
45
7
315
17
289

50-60
55
12
660
7
49

60-70
65
15
975
3
9

70-80
75
8
600
13
169

80-90
85
3
255
23
529

90-100
95
2
190
33
1089

class mark=lower limit+upperl imit2x=∑1n xifi∑1n fi=310050=62standar deviation=∑1n xi-x∑1n fi=12350=2
46Vriance σ2=∑1n xi-x2∑1n fi=286250=57
24

Classes	Class mark $(x_{i})$	frequency $(f_{i})$	$x_{i}$ $f_{i}$	$\|x_{i} - x\|$	${(x_{i} - x)}^{2}$
30-40	35	3	105	27	729
40-50	45	7	315	17	289
50-60	55	12	660	7	49
60-70	65	15	975	3	9
70-80	75	8	600	13	169
80-90	85	3	255	23	529
90-100	95	2	190	33	1089

​​Calculate mean,variance,standard deviation for the following distribution ​Classes- 30-40 40-50 50-60 60-70 70-80 80-90 90-100 frequency 3 7 12 15 8 3 2

Calculate mean,variance,standard deviation for the following distribution
Classes- 30-40 40-50 50-60 60-70 70-80 80-90 90-100
frequency 3 7 12 15 8 3 2