📚 Statistics & Percentiles
Percentiles tell you what percentage of data falls below a certain value. They're used in test scores, income data, growth charts, and more.
Understanding Percentiles:
💡 Real-World Example
On a standardized test, if you scored at the 85th percentile, it means you performed better than 85% of test-takers.
Quartiles and IQR:
Quartiles divide data into four equal parts:
- Q1 (25th percentile) - First quartile
- Q2 (50th percentile) - Second quartile (median)
- Q3 (75th percentile) - Third quartile
IQR (Interquartile Range) = Q3 - Q1
IQR represents the middle 50% of the data and is useful for identifying outliers.
Example: Income Percentiles
If the median household income is $70,000 and you earn $91,000:
🎯 Try It Yourself
Try It Yourself
In a test with scores sorted, if you scored higher than 85 out of 100 students, what percentile are you at?
Try It Yourself
If the median household income is $70,000 and yours is $91,000 at the 75th percentile, what percentage of households earn less than you?
📝 Final Quiz
Test what you learned. Pick the correct answer for each question.
1. A test score is in the 90th percentile. This means:
2. The median is the:
3. Q3 (third quartile) corresponds to which percentile?
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Put your knowledge into practice with our easy-to-use percentage calculator.
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