Let A assumed mean be 15.
Class interval |
Mid value (xi) |
di = xi -15 |
ui = \(\frac{xi-15}{6}\) |
fi |
fiui |
0 - 6 |
3 |
-12 |
-2 |
6 |
-12 |
6 - 12 |
9 |
-6 |
-1 |
8 |
-8 |
12 - 18 |
15 |
0 |
0 |
10 |
0 |
18 - 24 |
21 |
6 |
1 |
9 |
9 |
24 - 30 |
27 |
12 |
2 |
7 |
14 |
|
|
|
|
N = 40 |
\(\sum\)fiui |
A = 15, h = 6
Mean = A + h x \(\frac{\sum f_ix_i}{N}\)
\(=15+6\times\frac{3}{40}\)
\(=15+0.45\)
\(=15.45\)