Calculate the probability of an event from its favorable and total outcomes, and optionally combine it with a second independent event using AND / OR.
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The probability of an event is its number of favorable outcomes divided by the total number of possible outcomes. For example, rolling a 4 on a standard six-sided die has 1 favorable outcome out of 6 total, a probability of 1/6, about 16.67%.
If you enter a second event, this calculator treats events A and B as independent (one doesn't affect the other's outcome). P(A and B), the probability both happen, is P(A) × P(B). P(A or B), the probability at least one happens, is P(A) + P(B) − P(A) × P(B), which avoids double-counting the overlap where both occur.
No, this calculator assumes events A and B are independent, meaning the outcome of one doesn't affect the other. Dependent events (like drawing cards without replacement) require conditional probability, which isn't covered by this calculator.
No, leave event B's fields at 0 to calculate the probability of event A alone.
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