14)
Vind out standard deviation and its coefficient of the following series:
Size
10
20
30
40
50
60
70
Frequency
6
8
16
15
33
11
12
Answers
Answered by
0
Scores
x Frequence
f fx Deviation from mean d=(x−
x
) d
2
fd
2
10 4 40 −19 361 1444
20 3 60 −9 81 243
30 6 180 +1 1 6
40 5 200 +11 121 605
50 2 100 +21 441 882
n=20 ∑fx=580 ∑fd
2
=3180
(i) Arithmetic mean =
x
=
n
∑fx
=
20
580
=29
∴Mean=
x
=29
(ii) σ=
n
∑fd
2
=
20
3180
=
159
=12.61
∴σ=12.61
(iii) C.V=
x
σ
×100=
29
12.61
×100=
29
1261
=43.48
∴C.V.=43.48
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