What is the formula to use median when more than ogive is given?
More than type
We can write the given table for more than type as follows.
Number of students (Cumulative frequency)
More than or equal to 0
More than or equal to 10
More than or equal to 20
More than or equal to 30
More than or equal to 40
More than or equal to 50
More than or equal to 60
More than or equal to 70
More than or equal to 80
More than or equal to 90
Construction of Ogive of more than type
The smooth curve drawn between the lower limits of class intervals and cumulative frequencies is called cumulative frequency curve or ogive (for more than type).
The method of construction of more than type ogive is same as the construction of less than type. For more than type ogive, we take the lower limits on x-axis and the cumulative frequencies on the y-axis. In the above table, the lower limits and the cumulative frequencies have been represented.
The ogive of more than type is obtained by plotting the points (0, 80), (10, 78), (20, 77), (30, 74), (40, 69), (50, 60), (60, 45), (70, 23), (80, 11), (90, 4).
The ogive of more than type of the previous table has been shown below.
Formula to find the median with the help of more than ogive
Number of observations, n = 80
Mark the point 40 on the vertical line and then draw a horizontal line from this point. Let this line intersect the ogive at point A. Now, draw a vertical line through A. Median is the point at which this vertical line intersects the horizontal line.
Hence, the median is 62(approximately).