Poisson Probability Formula:
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Definition: This calculator computes the probability of a given number of events occurring in a fixed interval using the Poisson distribution.
Purpose: It's used in statistics, queuing theory, and other fields to model rare events occurring independently at a constant average rate.
The calculator uses the formula:
Where:
Explanation: The formula calculates the probability of observing exactly x events when the average rate is λ.
Details: Poisson processes are fundamental in modeling random events like customer arrivals, radioactive decay, or network traffic.
Tips: Enter the mean rate (λ) and the number of events (x) you want to calculate probability for. Both must be ≥ 0.
Q1: When should I use the Poisson distribution?
A: When events are independent, occur at a known constant rate, and the probability of more than one event in a small interval is negligible.
Q2: What's a typical value for λ?
A: λ represents the average rate - it could be 0.1 calls/hour for a help desk or 5 packets/second for network traffic.
Q3: Can x be a decimal?
A: No, x must be a non-negative integer (0, 1, 2,...) as it represents count of events.
Q4: What if I need cumulative probability?
A: You would need to sum probabilities for all values up to x (not implemented in this calculator).
Q5: How accurate are the results?
A: Results are mathematically exact for a true Poisson process, but real-world applications may have deviations.