Example 1 · level 1
A card is drawn at random from a well-shuffled deck of 52 cards. Find the probability that it is a spade.
Show solution
- P(a spade) = 13/52.
- = 1/4.
Answer: 1/4
CLASS 11 MATHS · PROBABILITY
Probability of events: cards, dice and unions
P(E) = favourable outcomes ÷ total outcomes. P(not E) = 1 − P(E). P(A ∪ B) = P(A) + P(B) − P(A ∩ B).
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Worked examples
Example 2 · level 2
Two fair dice are thrown together while playing Ludo. Find the probability that at least one die shows a 6.
Show solution
- Favourable outcomes = 11.
- P = 11/36 = 11/36.
Answer: 11/36
Example 3 · level 3
In a college in Lucknow, the probability that a student plays cricket is 1/5, plays badminton is 2/5, and plays both is 3/20. Find the probability that a student plays neither game.
Show solution
- P(A ∪ B) = 9/20 = 9/20.
- P(neither) = 1 − 9/20 = 11/20.
Answer: 11/20