Compute the mean of the following data, using direct method:
Class | 0 - 100 | 100 - 200 | 200 - 300 | 300 - 400 | 400 - 500 |
Frequency | 6 | 9 | 15 | 12 | 8 |
For equal class intervals, we will solve by finding mid points of these classes using direct method.
CLASS | MID - POINT(xi) | FREQUENCY(fi) | fixi |
0 - 100 | 50 | 6 | 300 |
100 - 200 | 150 | 9 | 1350 |
200 - 300 | 250 | 15 | 3750 |
300 - 400 | 350 | 12 | 4200 |
400 - 500 | 450 | 8 | 3600 |
TOTAL | 50 | 13200 |
We have got
Σfi = 50 & Σfixi = 13200
∵ mean is given by
⇒ 
⇒ 
Thus, mean is 264
6