| Marks | 20 | 70 | 50 | 60 | 75 | 90 | 40 |
| No. of students | 8 | 12 | 18 | 6 | 9 | 5 | 12 |
Calculate the median marks.
Solution:
We write the marks in ascending order in cumulative frequency table.
| Marks | No. of students (f) | Cumulative frequency |
| 20 | 8 | 8 |
| 40 | 12 | 20 |
| 50 | 18 | 38 |
| 60 | 6 | 44 |
| 70 | 12 | 56 |
| 75 | 9 | 65 |
| 90 | 5 | 70 |
Here total number of observations, n = 70 which is even.
Median = ½ ( n/2 th term + ((n/2)+1)th term)
= ½ (70/2 th term + ((70/2)+1)th term)
= ½ (35 th term + (35+1)th term)
= ½ (35 th term + 36th term)
= ½ (50+50) [Since all observations from 21st to 38th are 50]
= ½ ×100
= 50
Hence the median is 50.