A chest physician observed that the distribution of forced expiratory volume (FEV) in 300 smokers had a median value of 2.5 litres with the first and third quailes being 1.5 and 4.5 litres respectively. Based on this data now many persons in the sample ra eexpectable have a FEV between 1.5 and 4.5 litres-
Here, it&;s given 1st and 3rd quaile, which includes 50% values . Here total is 300. So 50% means 150
75
150
225
300
Biostatistics