4. The following distribution gives the state-wise teacher-student ratio in higher secondary schools of India. Find the mode and mean of this data. Interpret the two measures.
The class having maximum frequency is the modal class.
The maximum frequency is 10 and hence the modal class = 30-35
Lower limit (l) of modal class = 30, class size (h) = 5
Frequency ( ) of the modal class = 10 frequency ( ) of class preceding the modal class = 9, frequency ( ) of class succeeding the modal class = 3
Thus, Mode of the data is 30.625
Now,
Let the assumed mean be a = 32.5 and h = 5
Class |
Number of states |
Class mark |
|||
15-20 | 3 | 17.5 | -15 | -3 | -9 |
20-25 | 8 | 22.5 | -10 | -2 | -16 |
25-30 | 9 | 27.5 | -5 | -1 | -9 |
30-35 | 10 | 32.5 | 0 | 0 | 0 |
35-40 | 3 | 37.5 | 5 | 1 | 3 |
40-45 | 0 | 42.5 | 10 | 2 | 0 |
45-50 | 0 | 47.5 | 15 | 3 | 0 |
50-55 | 2 | 52.5 | 20 | 4 | 8 |
=35 |
= -23 |
Mean,
Thus, the Mean of the data is 29.22