Class | 0−20 | 20−40 | 40−60 | 60−80 | 80−100 |
Frequency | 15 | 18 | 21 | p | 17 |
Class |
Mid values (xi) |
Frequency (fi) |
fixi |
|
|
|
|
0-20 |
10 |
17 |
170 |
20-40 |
30 |
P |
30p |
40-60 |
50 |
32 |
1600 |
60-80 |
70 |
24 |
1680 |
80-100 |
90 |
19 |
1710 |
|
|
Total=92+p |
|
Mean(¯¯¯x)=∑fixi∑fi
50=5160+30p92+p
Therfore,
p=28