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Statistics
Medium trendapprox. 6 marksSections B/C/D — one full mean/median/mode computation from a frequency table, plus a short modal-class or empirical-relationship item.
CBSE 2027 — dates, rules and official papers →Ask the tutor1Show the cumulative-frequency (or fᵢxᵢ / fᵢuᵢ) column explicitly and state which class is the median/modal class before substituting — the table and class-identification each carry their own marks, and a final answer without them loses working marks.
Notesformulae · proofs · mind-map — one view
Learn the 4 conceptsteach yourself first, then practise each
Mean of grouped data — direct, assumed-mean & step-deviation (x̄ = Σfᵢxᵢ/Σfᵢ)2–3 marks Visual
Compute the average from a frequency table — pick the method that keeps the arithmetic lightest.
Median of grouped data: Median = l + ((n/2 − cf)/f)×h3–5 marks Visual
Find the middle value from the cumulative-frequency table in one substitution.
Mode of grouped data: Mode = l + ((f₁ − f₀)/(2f₁ − f₀ − f₂))×h2–3 marks Visual
Locate the most frequent value using the modal (highest-frequency) class.
Empirical relationship: Mode = 3 Median − 2 Mean1–2 marks Visual
Recover the third measure when two are already known, with no fresh table.
When you’re ready — practise or test the whole topic