Find the median from the following data.

Age in years	20-30	30-40	40-50	50-60	60-70	70-80	80-90
No. of Patients	12	16	30	20	17	38	15

Correct option is C

Formula Used:
​$$\text{Median} = L + \left( \frac{\frac{N}{2} - CF}{f} \right) \times h$$​​
Where:
- L = lower boundary of median class
- N = total frequency
- CF = cumulative frequency before median class
- f = frequency of median class
- h = class width
Solution:

Total frequency N = 148
​$$\frac N2$$​= 74
The cumulative frequency just greater than 74 is 78, so the median class is 50–60
Now apply the formula:
L = 50
N = 148
CF = 58
f = 20
h = 10
Median = $$50 + \left(\frac{74 - 58}{20}\right) \times 10 = 50 + \left(\frac{16}{20}\right) \times 10 = 50 + 8 = 58$$​​