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CalcivoTools

Probability Calculator : Single Event, Union (A ∪ B) & Conditional Probability P(A|B)

The Calcivo Probability Calculator solves single-event and two-event probability models. It computes exact fractions, percentages, complements (P(A')), odds in favor, union probabilities (P(A ∪ B)), and conditional probabilities (P(A|B)).

Interactive Calculator

100% Client-Side Engine
Event Probability P(A)
50% (0.5)
Complement P(A')
50% (0.5)
Odds in Favor
3 : 3
Odds Against
3 : 3
Mathematical Derivation
1. Probability P(A) = Favorable / Total = 3 / 6 = 0.5 (50%)
2. Complement P(A') = 1 - P(A) = 1 - 0.5 = 0.5 (50%)
3. Odds in Favor = Favorable : Unfavorable = 3 : 3
4. Odds Against = Unfavorable : Favorable = 3 : 3

Step-by-Step Examples

Rolling an Even Number on a 6-Sided Die

3 favorable outcomes (2, 4, 6) out of 6 possible.

Inputs: Favorable Outcomes: 3, Total Outcomes: 6
Result: 50.00% (0.5000, Odds: 3 : 3 = 1 : 1)

P(A) = 3 / 6 = 0.5 (50%). Complement P(A') = 0.5 (50%).

How to Use This Tool

  1. Select Single Event or Two Events mode.
  2. For single event: enter favorable outcomes and total possible outcomes.
  3. For two events: enter probabilities P(A) and P(B) and select event relationship.
  4. Click Calculate to see probability percentages, odds, and derivations.

Frequently Asked Questions

Mutually exclusive events cannot happen at the same time; their intersection is zero: P(A ∩ B) = 0, so P(A ∪ B) = P(A) + P(B).

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