Question

From the following frequency, prepare the ‘more than’ ogive.

Score	Number of candidates
400 – 450	20
450 – 500	35
500 – 550	40
550 – 600	32
600 – 650	24
650 – 700	27
700 – 750	18
750 – 800	34
Total	230

Also, find the median.

Answer 1

From the given table, we may prepare than ‘more than’ frequency table as shown below:

Score	Number of candidates
More than 750	34
More than 700	52
More than 650	79
More than 600	103
More than 550	135
More than 500	175
More than 450	210
More than 400	230

We plot the points A(750, 34), B(700,52),
C(650, 79), D(600, 103), E(550, 135), F(500, 175),
G(450, 210) and H(400, 230).
Join AB, BC, CD, DE, EF, FG, GH and HA with
a free hand to get the curve representing the
‘more than type’ series.

Here, N = 230
⇒ `N/2 = 115`
From P (0, 115), draw PQ meeting the curve at Q. Draw QM meeting at M.
Clearly, OM = 590 units
Hence, median = 590 units.