Hg
Name: Class 9
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The Hg Classes (8
th
to 12
th
) By: Er Hershit Goyal (B.Tech. IIT BHU), 134-SF, Woodstock Floors, Nirvana Country, Sector 50, GURUGRAM +91 9599697178.
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Statistics
1. Data – Facts, figures or information collected with a specific purpose is called Data.
2. Statistics is the branch of mathematics that deals with presentation, analysis and interpretation of data.
3. Data collected by the investigator himself is called primary data.
4. Data obtained from another source, that already had the information, is called secondary data.
5. Raw data is the original data not necessarily in a presentable or understandable form. It can be organised to
make more meaningful and analysis friendly in the following ways:
6. The number of times a particular observation is repeated is called frequency of that observation.
7. Tabular form can either be:
a.) Ungrouped frequency distribution table or simply frequency distribution table
b.) Grouped frequency distribution table
Presenting data in this form simplifies and condenses data and enables us to observe certain important features
at a glance.
8. The groupings in a grouped frequency distribution table are called classes or class-intervals and their size is
called class-size or class-width.
e.g. 10-20, where 10 is the lower class limit and 20 is the upper class limit.
9. Class mark is the mid-point of lower & upper class limits.
10. Mean or Average = =
=
=
=
11. Median is the middle most value of the data arranged in ascending (or descending) order.
12. Mode is the most frequently occurring observation.
Tabular Form
Bar Graph
Histogram
Frequency Polygon
Pie Charts
Pictogram
If n is odd:
Median is the
observation.
If n is even:
Median is the mean of
and
observations.
n = total number of observations.
