Probability Calculator – Guide & Formulas
Calculate the probability of single, multiple, independent, and union events. Features intuitive guides for intersection, addition, and conditional rules.
Analyze and compute probability ratios for independent, dependent, and mutually exclusive events. Learn how combinations determine chances in gaming and risk assessment.
Key Takeaway
Use the free Probability Calculator to calculate the probability of single, multiple, independent, and union events. features intuitive guides for intersection, addition, and conditional rules. Get instant results with step-by-step explanations.
How to Use the Probability Calculator
- Select the probability mode (Single, Two Independent, or Union).
- Input individual event probabilities as decimals (0 to 1) or percentages.
- Review the resulting conditional, intersection, and union likelihood percentages.
- Copy the detailed probability report with one click.
The Formula
Variable Definitions
- P(A): Probability of event A
- P(B): Probability of event B
- P(A ∩ B): Intersection probability (both occurring)
Rolling Dice and Flipping Coins
Find the probability of rolling a 6 on a die (Event A) AND flipping heads on a coin (Event B) simultaneously.
- Step 1: Input P(A) = 1/6 ≈ 0.1667.
- Step 2: Input P(B) = 1/2 = 0.5000.
- Step 3: Multiply the independent events: 0.1667 * 0.5 = 0.0833.
- Step 4: The combined probability is 8.33%.
Frequently Asked Questions
What makes events independent?
Events are independent if the occurrence of one does not affect the likelihood of the other occurring.
Why must probabilities fall between 0 and 1?
A probability of 0 represents absolute impossibility, while a probability of 1 represents absolute certainty. It is impossible to have less than a 0% chance or more than a 100% chance of an event.
What is conditional probability?
It measures the probability of an event occurring given that another event has already occurred. This is represented as P(A|B).