The Probability Calculator helps you determine the likelihood of events. Calculate single event probability, complementary probability, and combined probabilities using union and intersection rules.
Enter the number of favourable outcomes and total possible outcomes to find the probability. The calculator displays results as fractions, decimals, and percentages.
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Probability measures the likelihood of an event occurring, expressed as a number between 0 (impossible) and 1 (certain). The basic formula is P(A) = number of favourable outcomes / total number of possible outcomes.
Key rules: the complement rule states P(not A) = 1 - P(A). The addition rule for mutually exclusive events is P(A or B) = P(A) + P(B). For independent events, P(A and B) = P(A) * P(B).
Problema: What is the probability of rolling a 4 on a fair six-sided die?
Solucion: Favourable: 1 (just the number 4). Total: 6 sides.
Respuesta: P = 1/6 = 0.1667 = 16.67%
Problema: What is the probability of drawing a heart from a standard deck?
Solucion: Favourable: 13 hearts. Total: 52 cards.
Respuesta: P = 13/52 = 1/4 = 25%
Problema: If the probability of rain is 30%, what is the probability of no rain?
Solucion: P(no rain) = 1 - P(rain) = 1 - 0.30
Respuesta: 70%
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