Statistics

Mean, median, and mode — the three basic measures of central tendency tested in RRB Statistics questions.

📖 ~4 min read 📐 RRB NTPC / Group D — Mathematics

Measure	Definition
Mean	Sum of all values ÷ Number of values (same as Average)
Median	The middle value when data is arranged in order (average of two middle values if count is even)
Mode	The value that occurs most frequently in the data set

Odd number of values (n): Median = value at position (n+1)/2
Even number of values (n): Median = average of values at positions n/2 and (n/2)+1

💡 Example: Data = 3, 7, 9, 12, 15 (5 values, odd) → Median = value at position 3 = 9

💡 A data set can have more than one mode (bimodal/multimodal) or no mode at all if every value occurs equally.

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