The following table shows the ages of the patients admitted in a hospital during a year:
Age (in years): | 5-15 | 15-25 | 25-35 | 35-45 | 45-55 | 55-65 |
No. of students: | 6 | 11 | 21 | 23 | 14 | 5 |
Find the mode and the mean of the data given above. Compare and interpret the two measures of central tendency.
We may compute class marks (xi) as per the relation
Xi=
Now, let assumed mean (A) = 30
Age(in years) | No. of patients(fi) | Class marks (xi) | di=xi-30 | fidi |
5-15 | 6 | 10 | -20 | -120 |
15-25 | 11 | 20 | -10 | -110 |
25-35 | 21 | 30 | 0 | 0 |
35-45 | 23 | 40 | 10 | 230 |
45-55 | 14 | 50 | 20 | 180 |
55-65 | 5 | 60 | 30 | 150 |
Total | 80 | 430 |
∑fi=80, ∑fidi=430
Mean=
= 30 + = 30+ 5.375
=35.38
It represents that on an average the age of patients admitted was 35.38 years. As we can observe that the maximum class frequency 23 belonging to class interval 35-45.
So, modal class= 35-45
Lower limit (l) of modal class =35
Frequency (f1) of the modal class=23
h=10,
Frequency (f0)of class preceding the modal class=21
Frequency (f2) of class succeeding the modal class =14
Now,
=
=35 + 1.81 =36.8years