6 Math Chapter 9 Data Handling

Chapter Notes and Summary
Data : word data means information in form of numerical figures. e.g., marks obtained by 10 students of a class in a monthly test are given below :
27, 21, 35, 41, 45, 15, 18, 46, 47, 28.
Raw data : Data obtained in original form is called raw data.
e.g., ages (in years) of 6 teachers in a school are :
30, 35, 45, 29, 39, 54.
The given data related to ages of 6 teachers in a school
Array : Arranging numerical figures in an ascending or a descending order is called an array. e.g., data in an ascending order.
i.e., 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 6, 6.
and data in an descending order i.e, 6, 6, 5, 5, 4, 4, 4 3, 3, 3, 2, 2, 1, 1, 1.
Tabulation of data : Arranging data in a systematic tabular form is called tabulation or presentation of data.
Observations : Each numerical figure in a data is called an observation.
Frequency of an observation : number of times a particular observation occurs is called its frequency.
Statistics : It is science which deals with collection, presentation, analysis and interpretation of numerical data.
Pictograph : representation of an information through pictures is called a pictograph.
Bar graph : In a bar graph, bars (rectangles) of uniform width are created horizontally or vertically with equal spacing between them.
• In a bar graph, heights (or length) of bars represent given number.
• Bar ( ) represented to each observation in data is called tally marks.
• Tally marks are in group of 4 ( ). 5th mark makes a bundle ( ). Tally marks help in counting large number.
• Using tally marks, data can be arranged in a tabular form and particular information can be obtained from data quickly.

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