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Probability
Medium trendapprox. 5 marksSections A/B/C — a 1-mark MCQ on an event's probability, a 2-mark complement/range item, and one 3-mark problem enumerating outcomes for two coins, two dice or a card draw.
CBSE 2027 — dates, rules and official papers →Ask the tutor1Always write the total number of outcomes and the number of favourable outcomes explicitly before dividing, and give the answer as a reduced fraction (or exact decimal) in [0, 1] — bald answers with no outcome count lose the method mark.
Notesformulae · proofs · mind-map — one view
Learn the 5 conceptsteach yourself first, then practise each
Theoretical probability P(E) = number of favourable outcomes / total number of outcomes1–3 marks
The default engine for every coin, die, card or marble question — count both totals and divide.
Complement rule P(not E) = 1 − P(E)1–2 marks
Get the 'at least / not' probability without recounting outcomes.
Range and event types: sure event = 1, impossible event = 0, 0 ≤ P(E) ≤ 11–2 marks
Sanity-check any answer and settle 1-mark true/false or fill-in items.
Equally likely outcomes on standard experiments (coins, dice, cards, marbles)1–2 marks Visual
Justify why each outcome carries the same weight before you count.
Sample space of compound experiments (two coins, two dice, drawing a card)3–5 marks Visual
List all 4, 36 or 52 outcomes to fix the denominator for 3-mark problems.
When you’re ready — practise or test the whole topic