The mean of the following data is 53, find the missing frequencies.
age in years -- 0-20, 20-40 40-60 60-80, 80-100
number of people--- 15, f1, 21, f2, 17, 100
We have the following table-
| Class interval | Mid value(x) | Frequency(f) | fx |
| 0-20 | 10 | 15 | 150 |
| 20-40 | 30 | f1 | 30f1 |
| 40-60 | 50 | 21 | 1021 |
| 60-80 | 70 | f2 | 70f2 |
| 80-100 | 90 | 17 | 1530 |
Now,
