Probability Fraction Calculator

Your details

Single event: one probability fraction. Two events: union, intersection and complement. Conditional: P(A given B) from individual probabilities.
Number of outcomes that satisfy the event (e.g. 3 red marbles out of 12).
Total number of equally likely outcomes in the sample space.
Probability (fraction)Unlikely
1/4

The probability expressed as a fully reduced fraction.

Probability (decimal)0.25
Probability (%)0.25%
Complement P(A') fraction3/4

Probability = 1/4 (25.00%)

  • Out of 12 equally likely outcomes, 3 produce the event and 9 do not.
  • As a decimal: 0.2500. As a percentage: 25.00%.
  • The complementary probability (event NOT occurring) is 3/4 or 75.00%.
  • The odds in favor of the event are 1/3 (favorable to unfavorable).

Next stepMultiply this probability by the number of trials to estimate the expected count of successes in repeated experiments.

 = Powered by OnlyCalculators