How Will Science and Technology Improve Our Future?What Should India Do to Stay Ahead in the Game

Topics: Binary relation, Cartesian coordinate system, Nontotient Pages: 2 (582 words) Published: November 26, 2012
Finding Median Graphically
Marks
inclusive series| Conversion into
exclusive series| No. of students| Cumulative Frequency|
(x)|  | (f)| (C.M)|
410-419| 409.5-419.5| 14| 14|
420-429| 419.5-429.5| 20| 34|
430-439| 429.5-439.5| 42| 76|
440-449| 439.5-449.5| 54| 130|
450-459| 449.5-459.5| 45| 175|
460-469| 459.5-469.5| 18| 193|
470-479| 469.5-479.5| 7| 200|
The median value of a series may be determinded through the graphic presentation of data in the form of Ogives.This can be done in 2 ways. 1. Presenting the data graphically in the form of 'less than' ogive or 'more than' ogive . 2. Presenting the data graphically and simultaneously in the form of 'less than' and 'more than' ogives.The two ogives are drawn together. 1.Less than Ogive approach

Marks| Cumulative Frequency (C.M)|
Less than 419.5| 14|
Less than 429.5| 34|
Less than 439.5| 76|
Less than 449.5| 130|
Less than 459.5| 175|
Less than 469.5| 193|
Less than 479.5| 200|
Steps involved in calculating median using less than Ogive approach - 1. Convert the series into a 'less than ' cumulative frequency distribution as shown above . 2. Let N be the total number of students who's data is given.N will also be the cumulative frequency of the last interval.Find the (N/2)th item(student) and mark it on the y-axis.In this case the (N/2)th item (student) is 200/2 = 100th student. 3. Draw a perpendicular from 100 to the right to cut the Ogive curve at point A. 4.From point A where the Ogive curve is cut, draw a perpendicular on the x-axis. The point at which it touches the x-axis will be the median value of the series as shown in the graph.

The median turns out to be 443.94.
2.More than Ogive approach
More than marks| Cumulative Frequency (C.M)|
More than 409.5| 200|
More than 419.5| 186|
More than 429.5| 166|
More than 439.5| 124|
More than 449.5| 70|
More than 459.5| 25|
More than 469.5| 7|...