A survey of heights (in cm) of 51 girls of class X of a school was conducted and the following data was obtained. Find the median height.
HEIGHT (IN CM)NUMBER OF GIRLSBELOW 1404140−1457145−15018150−15511155−1606160−1655
CLASS INTERVALSFREQUENCYCUMULATIVE FREQUENCYBELOW 14044140−145711145−1501829150−1551140155−160646160−165551CUMULATIVE FREQUENCY51
n = 51
(n2)=25.5
So, the cumulative frequency of class is corresponding to class-interval 145-150.
l (lower limit) =145,
Cumulative frequency of class preceding 145-150 = 11
f (frequency of median class) = 18
h (size of class-interval) = 5
Median =l+(n2−1f)h=145+(25.5−1118)×5=149.03