The following table shows the age distribution of patients of malaria in a village during a particular month:

Age (in years)	No. of cases
5-14	6
15-24	11
25-34	21
35-44	23
45-54	14
55-64	5

The average age of the patients is ____ years.

Age (in years)

No. of cases

5-14

6

15-24

11

25-34

21

35-44

23

45-54

14

55-64

5

Class Interval

Frequency, $f_i$

Mid-value, $x_i$

$u_i$=$\frac{x_i-A}{h}$=$\frac{x_i-29.5}{10}$

$f_i{u}_i$

4.5-14.5

6

9.5

-2

-12

14.5-24.5

11

19.5

-1

-11

24.5-34.5

21

29.5=A

0

0

34.5-44.5

23

39.5

1

23

44.5-54.5

14

49.5

2

28

54.5-64.5

5

59.5

3

15

Σ$f_i$=80

Σ$f_i{u}_i$=80