Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
Frequency | 6 | 7 | 15 | 16 | 4 | 2 |
Class | Frequency fi | c.f | Class−mark xi | |xi−M| (xi−28) | fi|xi−M| |
0−10 | 6 | 6 | 5 | 23 | 138 |
10−20 | 7 | 13 | 15 | 13 | 91 |
20−30 | 15 | 28 | 25 | 3 | 45 |
30−40 | 16 | 44 | 35 | 7 | 112 |
40−50 | 4 | 48 | 45 | 17 | 68 |
50−60 | 2 | 50 | 55 | 27 | 54 |
∑fi=50 | ∑fi|xi−M|=508 |