OhMyCalc

Probability Calculator

Calculate probability for single events, unions, intersections, and conditional probability. Supports all basic probability operations.

How to Use the Probability Calculator

  1. Enter your data set or statistical values in the input fields.
  2. Click Calculate to process the data.
  3. Review the computed result with detailed breakdown.
  4. Modify inputs or add more data points for further analysis.

快速参考

Mean [2,4,6]4
Median [1,3,5,7]4
Mode [2,2,3,5]2
σ [2,4,4,4,5,5,7,9]2
z-score (x=85, μ=70, σ=10)1.5
P(A)+P(B)−P(A∩B)P(A∪B)

使用场景

公式

Single: P = favorable/total. Union: P(A∪B) = P(A) + P(B) − P(A∩B). Intersection: P(A∩B) = P(A) × P(B). Conditional: P(A|B) = P(A∩B) / P(B).

常见问题

What is probability?
Probability measures the likelihood of an event occurring, expressed as a number between 0 (impossible) and 1 (certain).
What is the union of two events?
The union P(A∪B) is the probability that event A or event B (or both) occurs. P(A∪B) = P(A) + P(B) − P(A∩B).
What is conditional probability?
Conditional probability P(A|B) is the probability of A occurring given that B has already occurred. P(A|B) = P(A∩B) / P(B).
When can I multiply probabilities?
You can multiply P(A) × P(B) to get P(A∩B) only when events A and B are independent — meaning one does not affect the other.