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Mathematics · Class 10 · Chapter 22: Basic Statistics
8 min
Key points
- Statistics is the science which deals with the collection, presentation, analysis and interpretation of numerical data
- Data can be classified as Primary Data (collected directly) and Secondary Data (obtained from other sources)
- Measures of Central Tendency include Mean, Median and Mode - these show the central value of data
- Arithmetic Mean = Sum of all observations ÷ Number of observations
- For grouped data, Mean = Σfx/Σf where f is frequency and x is class mark
- Median is the middle value when data is arranged in ascending or descending order
- Mode is the value that occurs most frequently in the data set
- Range = Highest value - Lowest value, measures the spread of data
- Frequency Distribution Table organizes raw data into classes with their frequencies
Definitions
- Statistics
- Statistics is the science which deals with the collection, presentation, analysis and interpretation of numerical data.
- Primary Data
- Primary data is the data collected directly by the investigator from the original source for the first time.
- Arithmetic Mean
- The arithmetic mean of a set of observations is the sum of all observations divided by the number of observations.
- Median
- The median is the middle value of the observations when they are arranged in ascending or descending order of magnitude.
- Mode
- The mode is the value which occurs most frequently in a set of observations.
Worked example
Calculate the arithmetic mean of the following data: 15, 18, 12, 20, 16, 14, 19, 13, 17, 11 (4 marks)
The arithmetic mean of the given data is 15.5
Common mistakes
- Students often forget to arrange data in order before finding median
- Confusing class mark with class interval in grouped data mean calculation
- Not writing the formula before solving numerical problems
- Mixing up definitions of primary and secondary data
- Forgetting to divide by total frequency (Σf) in grouped data mean formula
Quick recap
Statistics is the science of collecting, organizing, presenting, analyzing and interpreting numerical data. Remember the exact textbook definitions of population (complete group), sample (part of population), variable (characteristic that changes), primary data (collected directly) and secondary data (already collected). For calculations, always show complete working with formulas for mean, median, and mode.
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