Evaluate chance outcomes for single and combined events.
Overview
Probability quantifies uncertainty and supports decisions in risk analysis, quality control, and experiments. Correct modeling starts with defining sample space and event relationships clearly.
Simple probabilities compare favorable outcomes to total outcomes, while combined-event probabilities require addition, multiplication, and conditional logic depending on independence and overlap.
This calculator helps with event unions, intersections, complements, and conditional probabilities. It is useful for students, analysts, and anyone estimating chance-based outcomes.
Steps
Choose simple, conditional, union, intersection, or complement mode.
Provide valid totals and event values.
State whether events are independent or related.
Run formula and inspect decimal, fraction, or percent output.
Translate numeric chance into practical risk language.
Math
P(A)=favorable/total; P(A union B)=P(A)+P(B)-P(A and B); P(A|B)=P(A and B)/P(B)
Combined-event formulas prevent double-counting overlap and adjust event likelihood when conditioning on known information.
Worked cases
4/52
P(ace) = 1/13 about 0.0769.
0.5 + 0.4 - 0.2
P(A union B) = 0.7.
0.18 / 0.3
P(A|B) = 0.6.
Why use this
Questions