The median of a group of numbers is the number in the middle, when the numbers are in the order of their magnitudes. For n numbers in a group, median is the (n+1)/2 th value. In case of cumulative frequency curve, n is the cumulative frequency.
By drawing horizontal lines to half of total frequency, the median can be found out from cumulative frequency curves.
First, construct the the cumulative frequency curve of the given values. Mark the highest cumulative frequency and draw a line parallel to the Y axis that exactly pass through this mark. Then mark the lowest cumulative frequency and draw a line parallel to the X axis. Mark the point of intersection of these two lines.
Now find the midpoint of the line connecting this point of intersection with the point marked at highest cumulative frequency. Again, draw a line parallel to the X axis, and passing through this midpoint that we just plotted. Where this line meets the cumulative frequency curve, the value on X axis at that point is the median of the Curve.