if the mean of the following distribution is 26.2
CLASSES : 0-10 10-20 20-30 30-40 40-50
FREQUENCY: 10 12 5 f 15
then f is
| Classes | Mid-point(m) | Frequency(f) | mf |
| 0-10 | 5 | 10 | 50 |
| 10-20 | 15 | 12 | 180 |
| 20-30 | 25 | 5 | 125 |
| 30-40 | 35 | f | 35f |
| 40-50 | 45 | 15 | 675 |
Total 42+f 1030+35f
Mean = 
⇒
⇒f = 8