Probability Flashcards

Grade 9 · Math · Flashcards

Key vocabulary and formulas for probability in Grade 9 Math.

Flashcards

Probability: P(event) = favorable outcomes ÷ total equally likely outcomes; range 0–1
Certain event: An event that always happens; P = 1
Impossible event: An event that never happens; P = 0
Complement: P(not A) = 1 − P(A)
Independent events: Outcome of one does not affect the other; P(A and B) = P(A)×P(B)
Dependent events: Outcome of one affects the other (e.g., drawing without replacement)
Mutually exclusive events: Cannot occur at the same time; P(A or B) = P(A) + P(B)
Overlapping events: Can occur simultaneously; P(A or B) = P(A) + P(B) − P(A and B)
Theoretical probability: Based on equally likely outcomes in theory
Experimental probability: Based on observed results from actual trials
Sample space: The set of all possible outcomes of an experiment
Law of Large Numbers: More trials → experimental probability gets closer to theoretical probability