We may compute class marks (xI) as per the relation
x1 \(=\frac{upper\,class\,limit+lower\,class\,limit}{2}\)
Now,
let assumed mean (A) = 30
∑fi=80, ∑fidi=430
Mean = A + \(\frac{\sum f_id_i}{\sum f_i}\)
\(=30+\frac{430}{80}=30+5.375\)
=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,
Mode = \(I+(\frac{f-f_0}{2f-f_0-f_2})h\)
\(=35+(\frac{23-21}{2(23)-21-14})10\)
=35 + 1.81 =36.8years