11. Following is the distribution of marks obtained by 60 students: Calculate the arithmetic mean
MarksMorethan 0more than 10More than20More than 30More than 40More than 50No ofstudents60564020103
xThe table can be given as,
Now using direct method for finding the mean of 60 student,
Mean = =
| More than | Cumulative frequency | Class | frequency(fi) | fi.xi |
| More than 0 | 60 | 0-10 | 4 | 20 |
| More than 10 | 56 | 10-20 | 16 | 240 |
| More than 20 | 40 | 20-30 | 20 | 500 |
| More than 30 | 20 | 30-40 | 10 | 350 |
| More than 40 | 10 | 40-50 | 7 | 315 |
| More than 50 | 3 | 50-60 | 3 | 165 |
Now using direct method for finding the mean of 60 student,
Mean = =