Statistics Class 9th Notes - Free NCERT Class 9 Maths Chapter 14 Notes - Download PDF

Statistics is an applied mathematics that deals with the collection, interpretation and analysis of data. Statistics is used to compute, manipulate or organise data. Many types of manipulation operations can be performed on large data sets. With the help of statistics, different types of data can be compared in a single frame. It is used to convert the raw data into useful information. There are many applications of statistics, like weather forecasting, probability, geology, psychology, and medical studies etc. Some real-life applications are in business, like marketing for comparing market trends.

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This Story also Contains

1. NCERT Class 9 Maths Chapter 12 Statistics: Notes
2. Graphical Representation of Data
3. Class 9 Chapter Wise Notes
4. NCERT Solutions for Class 9
5. NCERT Exemplar Solutions for Class 9
6. NCERT Books and Syllabus

In these notes, students learn the definition of statistics and its basic concepts, such as data, frequency, types of data, class intervals and their types, and related formulae, such as mean, mode, or median. The CBSE Class 9 chapter includes questions and examples for the given topics as required. In these NCERT class 9th maths notes, all the chapters, topics, and subtopics are covered according to the latest syllabus. Students from different standards can download the NCERT notes according to their requirements.

NCERT Class 9 Maths Chapter 12 Statistics: Notes

Statistics

A branch of mathematics concerned with data collection, analysis, interpretation and presentation is known as statistics.

Data

Any numerical or non-numerical figures, facts or other information that is collected for a particular purpose is called data.

Frequency

The number of occurrences of a particular datum is called the frequency.

Ungrouped Data

When the observation is not organised in groups, then this type of data is called ungrouped data.

Grouped Data

When the observations are organised in groups, this is called grouped data.

Class Interval

The size of the data on which the class is divided is called the class interval.

Class width = upper class limit – lower class limit

Regular and Irregular Class Interval

When the class interval is of the same size, it is called a regular class interval.
Example: 0 - 10, 10 - 20, 20 - 30, 30 - 40

When the class interval is of a different size, it is called an irregular class interval.
Example: 0 - 10, 10 - 35, 35 - 45, 45 - 60

Frequency Table

It shows the occurrence of a particular variable in a tabular form.

Sorting

Arranging data in a particular order (ascending or descending order) is called sorting data.

Ungrouped Frequency Table

A frequency table in which data is not arranged in any particular order, then is called an ungrouped frequency table.

Grouped Frequency Table

A frequency table in which data is arranged in any particular order, either in ascending or descending order then is called a grouped frequency table.

Graphical Representation of Data

Some of the graphical representations of data are as follows.

Bar Graphs

Bar graphs represent data using bars of equal width and space between them on the axis. The frequency of data is represented through the height of the bar. Bar graphs are used for discrete data intervals.
For example:

The representation of these data in a bar graph is as follows.

Histograms

Similar to the bar graph, histograms are also used for the graphical representation of data, but this is used for continuous data intervals. In this graph, the area of the rectangle or frequency represented by the height of the graph and width is called the class intervals.

Frequency Polygon

When the midpoints of each rectangle are joined by using line segments in the histogram, this is called the frequency polygon. It can be drawn without a histogram.

Midpoint of the Class Interval

The class mark or the midpoint of the circle can be calculated as:

Class mark = $\frac{(Upperlimit+Lowerlimit)}{2}$

A frequency polygon can be drawn using the given class mark.

Example: In a company, employees of different departments work for different numbers of months and the tabular data is shown below. Draw the histogram for the table shown below.

Class mark = $\frac{(Upperlimit+Lowerlimit)}{2}$

Class mark = $\frac{(100+50)}{2}$ = 75

Similarly, determine the class mark for all values.

The histogram for the given tabular data is shown below; in this graph, ABCDEF is called the frequency polygon.

Class 9 Chapter Wise Notes

Students must download the notes below for each chapter to ace the topics.

NCERT Solutions for Class 9

Students must check the NCERT solutions for Class 10 Maths and Science given below:

• NCERT Solutions for Class 9 Maths
• NCERT Solutions for Class 9 Science

NCERT Exemplar Solutions for Class 9

Students must check the NCERT exemplar solutions for Class 10 Maths and Science given below:

• NCERT Exemplar Class 9 Maths Solutions
• NCERT Exemplar Class 9 Science Solutions

NCERT Books and Syllabus

To learn about the NCERT books and syllabus, read the following articles and get a direct link to download them.

• NCERT Syllabus for Class 9
• NCERT Books for Class 9