Page 60 - DECO504_STATISTICAL_METHODS_IN_ECONOMICS_ENGLISH

Statistical Methods in Economics

Notes 30—40 17
40—50 6
50—60 4

The mean of the distribution is 30.2 marks.
Solution: Let x be the missing frequency.
Marks M.V. (m) frequency (f) m.f.
0—10 5 4 20
10—20 15 7 105
20—30 25 x 25x
30—40 35 17 595
40—50 45 6 270
50—60 55 4 220
n = 38 + x ∑mf = 1210 + 25x

∑mf 1210 + 25x
a = or 30.2 =
n 38 + x
or 30.2 (38 + x) = 1210 + 25 x
or 1147.6 + 30.2 x = 1210 + 25 x
or 30.2 x – 25 x = 1210 – 1147.6
or 5.2 x = 62.4
x = 12
The missing frequency is, therefore, 12.
Answer: 12.
Example 7: Calculate the Geometric Mean of the following two series:
Series A Series B
173 0.8974
182 0.0570
75 0.0081
5 0.5677
0.8 0.0002
0.08 0.0984
0.8974 0.0854
0.5672
Solution:
Series A Series B

Values logs Values logs
173 2.2380 0.8974 1.9530
185 2.2601 0.0570 2.7559
75 1.8751 0.0081 3.9085
5 0.6990 0.5677 1.7541

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