Class 9 Maths — Chapter 12: STATISTICS
Chapter 12: STATISTICS is a chapter in Class 9 Maths (NCERT), part of the CBSE NCERT curriculum followed by over 25 million students across India. This chapter covers 6 topics including Interpreting Bar Graphs, Constructing Bar Graphs, Distinguishing Bar Graphs and Histograms. BrainWeave provides free AI-powered explanations — by voice or text, in Hindi or English — with no signup required.
What you'll learn
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▸Interpreting Bar Graphsbar graphread datacompare valuescategorical datauniform width
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▸Constructing Bar GraphsCore conceptconstructdraw bar graphscaleaxesdiscrete data
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▸Distinguishing Bar Graphs and Histogramsbar graph vs histogramdiscrete datacontinuous datagapsclass interval
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▸Histograms for Uniform WidthCore concepthistogramuniform widthcontinuous class intervalsfrequency distributionno gaps
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▸The Principle of Proportional Area in HistogramsCore conceptareaproportionalfrequencyrectangleclass width
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▸Histograms for Varying Widthsvarying widthsunequal class intervalsadjusted frequencyminimum class sizemodified length
Chapter Summary
Understanding how to read and extract specific data points and make comparisons from a given bar graph, which represents categorical data with bars of uniform width.
Learning the step-by-step process of creating a bar graph from a set of discrete data, including choosing appropriate scales for the axes, drawing bars of uniform width with equal spacing, and correctly representing the data values.
Identifying the key differences between a bar graph and a histogram. Bar graphs are used for discrete/categorical data with gaps between bars, while histograms are for continuous data with no gaps, where the width of the bar is meaningful.
Understanding and constructing histograms for grouped frequency distributions with continuous and equal-sized class intervals. This includes representing class intervals on the horizontal axis and frequencies on the vertical axis, with no gaps between the bars.
Understanding the fundamental concept that in a histogram, the area of each rectangular bar is proportional to the frequency of the corresponding class interval. This principle is crucial for correctly constructing all histograms.
Learning the technique for drawing a histogram when the class intervals have different widths. This involves adjusting the lengths of the rectangles to ensure their areas are proportional to the frequencies, by calculating the adjusted frequency based on a minimum class size.
Practice Questions from this Chapter
Tap "Get Solution" on any question to ask our AI tutor.
- Compare bar graphs to pie charts. Get Solution →
- Show real-life data visualization examples. Get Solution →
- Explain how data predicts future trends. Get Solution →
- What is a pictorial representation of data where bars of uniform width are drawn with equal spacing between them on one axis? Get Solution →
- According to the definition of a bar graph, what do the heights of the bars depend on? Get Solution →
- From the bar graph in Fig. 12.1, how many students were born in the month of November? Get Solution →
- Which graphical representation is specifically used for continuous class intervals? Get Solution →
- In the histogram shown in Fig. 12.3, what is indicated by a 'kink' or 'break' on the horizontal axis? Get Solution →
Did you know?
- 💡 The word 'statistics' originated from the Latin for 'state affairs' or 'council of state'.
- 💡 Florence Nightingale used statistical graphs to convince British officials to improve army sanitation.
- 💡 The first bar chart was created in 1786 by William Playfair to show imports and exports.
- 💡 Many famous statisticians were actually mathematicians, like Carl Friedrich Gauss.
- 💡 Maps of stars from ancient Egypt show early attempts at visual data representation.
Frequently Asked Questions
How many topics are covered in this chapter?
This chapter covers 6 key topics: Interpreting Bar Graphs, Constructing Bar Graphs, Distinguishing Bar Graphs and Histograms, Histograms for Uniform Width, The Principle of Proportional Area in Histograms, and more. The BrainWeave AI tutor explains each one with examples.
Is Chapter 12: STATISTICS important for board exams?
Class 9 is a foundation year. Mastering this chapter now will help you build strong fundamentals for the higher classes.
Can I get NCERT solutions for this chapter in Hindi?
Yes. BrainWeave's AI tutor supports Hindi, English, and Hinglish for both voice and text chat. Just ask your question in your preferred language.
Is BrainWeave free for Class 9?
Yes. BrainWeave's free Spark plan gives generous daily messages — enough for regular homework. Premium features unlock when you bring your own free Google Gemini API key.
Can I use voice chat for this chapter?
Absolutely. Tap the mic, ask any question about Chapter 12: STATISTICS, and the AI tutor will explain it back in voice and text.
How is BrainWeave better than static NCERT solutions sites?
Static solution sites give the same answer to everyone. BrainWeave adapts to your question — ask "explain like I'm 12" or "give a real-world example" and get a personalized response. Voice mode and Hindi support work seamlessly.
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