Class 7 | Ganita Prakash Part-II | Chapter 5
๐ Connecting the Dotsโฆ
Statistics ยท Mean ยท Median ยท Mode ยท Graphs
โ 5.1 โ Statistical Questions
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What is a Statistical Question?
A question that requires data collection and has variability in answers.
Statistical โ : "How tall are Grade 7 students?"
(answers vary โ need data)
NOT Statistical โ: "What is 5 + 3?"
(single definite answer)
A question that requires data collection and has variability in answers.
Statistical โ : "How tall are Grade 7 students?"
(answers vary โ need data)
NOT Statistical โ: "What is 5 + 3?"
(single definite answer)
Statistics = Collect โ Organise โ Analyse โ Interpret โ Present
We use statistics to make sense of the world around us!
Examples of statistical statements:
"Batting average of Shubman", "Rainfall last year", "Price of onions in different cities"
We use statistics to make sense of the world around us!
Examples of statistical statements:
"Batting average of Shubman", "Rainfall last year", "Price of onions in different cities"
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๐ 5.2 โ Representative Values
Three main measures of central tendency:
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1. MEAN (Average) ๐
Mean = (5+8+10+7+10) รท 5 = 40 รท 5 = 8
Mean = Sum of all values รท Number of values
Data: 5, 8, 10, 7, 10Mean = (5+8+10+7+10) รท 5 = 40 รท 5 = 8
2. MEDIAN (Middle value) ๐
Arrange data in order: 5, 7, 8, 10, 10
If odd count: middle value = 8
If even count: average of two middle values
3. MODE (Most frequent) ๐
Data: 5, 7, 8, 10, 10
10 appears TWICE โ Mode = 10
Can have more than one mode, or no mode!
Data: 5, 7, 8, 10, 10
10 appears TWICE โ Mode = 10
Can have more than one mode, or no mode!
๐ Cricket Example!
Shubman: 0, 17, 21, 90 โ Mean = 128/4 = 32 Median = (17+21)/2 = 19
Yashasvi: 67, 55, 18, 35 โ Mean = 175/4 = 43.75 Median = (35+55)/2 = 45
Yashasvi has higher mean AND median โ more consistent performer!
Shubman: 0, 17, 21, 90 โ Mean = 128/4 = 32 Median = (17+21)/2 = 19
Yashasvi: 67, 55, 18, 35 โ Mean = 175/4 = 43.75 Median = (35+55)/2 = 45
Yashasvi has higher mean AND median โ more consistent performer!
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๐ 5.3 โ Visualising Data
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| Type | Best for | How it looks |
|---|---|---|
| Bar Graph | Comparing categories | Vertical/horizontal bars |
| Pictograph | Simple picture data | Pictures/symbols |
| Line Graph | Trends over time | Points connected by lines |
| Pie Chart | Parts of a whole | Circle divided in sectors |
| Histogram | Frequency of ranges | Bars touching each other |
Reading Graphs โ Always check:
- Title โ what is the graph about?
- Axes labels โ what are x and y showing?
- Scale โ what does each unit represent?
- Legend/key โ what do colours/symbols mean?
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๐ 5.4 โ Data Detective
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Being a Data Detective means:
- Questioning whether a graph is misleading
- Checking if the scale starts at 0 (or is it manipulated?)
- Thinking about what data is missing
- Looking for trends and outliers
- Asking "Who collected this data and why?"
โ ๏ธ Misleading Statistics!
"Average salary = โน50,000" โ but if one person earns โน5,00,000 and others earn โน10,000, the mean is very misleading!
โ Median would be more representative here!
Always think critically about data!
"Average salary = โน50,000" โ but if one person earns โน5,00,000 and others earn โน10,000, the mean is very misleading!
โ Median would be more representative here!
Always think critically about data!
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๐ Quick Cheatsheet
Mean = Sum รท n
Add all, then
divide by count
Add all, then
divide by count
Median = middle
Sort first!
Odd: middle; Even: avg
Sort first!
Odd: middle; Even: avg
Mode = most
frequent value
Can be multiple!
frequent value
Can be multiple!
Graph types:
Bar, Line, Pie,
Pictograph, Histogram
Bar, Line, Pie,
Pictograph, Histogram
| Measure | Formula/Method | Best when... |
|---|---|---|
| Mean | Sum รท Count | No extreme outliers |
| Median | Sort, find middle | Outliers present (income, house prices) |
| Mode | Most repeated value | Categorical data (favourite colour, shoe size) |
๐ Chapter 5 Complete! ๐
Made with โค๏ธ by @edugrown
Made with โค๏ธ by @edugrown