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60-80 35 Less than 80 80(45+35) (80,80)
80-100 20 Less than 100 100(80+20) (100,100)
Graph work(graph paper should be used for this Ogive)

Here, N = 100

Taking a point A(0, 50) on y-axis and draw AP||x-axis meeting the curve at P.
Draw PM x-axis.
OM = 62.8
Hence, median = 62.8

Notes:
(i)The Scale may not be the same on both axes
(ii)If we join the points by straight lines instead of free hand,we get a frequency polygon
(iii)For drawing an ogive, it should be ensured that the class intervals are continuous.If
class intervals are not continuous, then convert them into continuous form.

Example-2: An agriculture research officer measured the heights (to the nearest
centimetre) of 100 test plants after two months of growth. The distribution of
heights is shown below:
Heights 1 - 5 6 - 10 11 - 15 16 - 20 21 - 25 26 - 30
Number of plants 3 5 9 31 38 14

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