The following data relate to the age of a group of gov. Employees. Calculate the arithmetic mean and standard deviation.
Age- 50-55. 45-50. 40_45. 35-40. 30-35. 25-30. 20-25
No.e-. 25. 30. 40. 45. 80. 110. 170
Answers
Answer:
X Mid point (x) Frequency (F) i=class interval width A=22.5 Assumed mean u=
i
x−A
fu
0-5 2.5 3 5 22.5 -4 -12
5-10 7.5 5 5 22.5 -3 -15
10 -15 12.5 7 5 22.5 -2 -14
15-20 17.5 8 5 22.5 -1 -8
20-25 22.5=A 10 5 22.5 0 0
25-30 27.5 11 5 22.5 1 11
30-35 32.5 14 5 22.5 2 28
35-40 37.5 19 5 22.
5 3 57
40-45 42.5 15 5 22.5 4 60
45-50 47.5 13 5 22.5 5 65
Σf=105 Σfu=172
The formula used for arithmetic mean of grouped data by step deviation method is,
X
=A+
∑f
∑fu
×i
A= Assumed mean of the given data
∑ = Summation of the frequencies given in the grouped data
∑fu = Summation of the frequencies and deviation of a given mean data
u=
i
(x−A)
i= Class interval width
X
= arithmetic mean
X
=22.5+
105
172
×5
=22.5+8.19
=30.69 ≈ 31