Question :
| Daily Wages in Rupees | 0 – 120 | 120 – 140 | 14 – 160 | 160 – 180 | 180 – 200 |
| Number of Workers | 12 | 14 | 8 | 6 | 10 |
Solution :
Let the assumed mean A = 150 and class size h = 50
So, \(u_i\) = \(x_i – A\over h\) = \(x_i – 150\over 20\)
Class Interval
Mid-value (\(x_i\))
Frequency (\(f_i\))
\(u_i\) = \(x_i – 150\over 20\)
\(f_iu_i\)
100 – 120
110
12
-2
-24
120 – 140
130
14
-1
-14
140 – 160
150
8
0
0
160 – 180
170
8
1
6
180 – 200
190
10
2
20
Total
50
-12
So, \(\bar{x}\) = A + h\(\sum f_iu_i\over f_i\) = 150 + 20 \(\times\) \(-12\over 50\)
= 150 – 4.8 = 145.2
Hence, mean = 145.20
