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	11	16	14	29	40	21	17

Correct option is D

Formula Used:

Median = L + $$\left( \frac{\frac{N}{2} - CF}{f} \right) \times h$$​​

Where:

L = lower boundary of the median class

N = total frequency

CF = cumulative frequency before median class

f = frequency of median class

h = class width

Solution:

Total frequency N = 148

​$$\frac{N}{2} = \frac{148}{2} = 74$$​​

The median class is 60 – 70, because 74 lies between 70 and 110

Now: L = 60, CF = 70, f = 40, h = 10

Median = 60 + $$\left( \frac{74 - 70}{40} \right) \times 10$$​​

= 60 + $$\left( \frac{4}{40} \right) \times 10$$​​

= 60 + 1 = 61