An incomplete distribution is given as follows:
Variable: 0 -10 10 - 20 20 - 30 30 - 40 40 - 50 50 - 60 60 - 70
Frequency: 10 20 ? 40 ? 25 15
You are given that the median value is 35 and the sum of all the frequencies is 170. Using the median formula, fill up the missing frequencies.
Class interval | Frequency | Cumulative frequency |
0 – 10 | 10 | 10 |
10 – 20 | 20 | 30 |
20 – 30 | f1 | 30 + f1 (F) |
30 – 40 | 40 (F) | 70 + f1 |
40 – 50 | f2 | 70 + f1 + f2 |
50 – 60 | 25 | 95 + f1 + f2 |
60 – 70 | 15 | 110 + f1 + f2 |
N = 170 |
Given
Median = 35
Then median class = 30 – 40
L = 30, h = 40 – 30 = 10, f = 40, F = 30 + f1
f1 = 55 – 20 = 35
Given
Sum of frequencies = 170
10 + 20 + fi + 40 + f2 + 25 + 15 = 170
10 + 20 + 35 + 40 + f2 + 25 + 15 = 170
f2 = 25
f1 = 35 and f2 =25