It looks like you're asking about calculating a probability using the Poisson distribution. To help you properly, I'll need the specific values you're working with, such as:

1. The mean rate (λ) — the average number of occurrences in a given interval.
2. The number of occurrences (k) — the specific number of events you want to calculate the probability for.

The general formula for the Poisson probability is:

$P(X = k) = \frac{\lambda^k e^{-\lambda}}{k!}$

Where:

• $P(X = k)$ is the probability of having exactly k events,
• $\lambda$ is the average number of events (mean rate),
• $k$ is the number of events for which you want the probability,
• $e$ is the base of the natural logarithm (approximately 2.71828).

Could you provide the values for $\lambda$ (mean rate) and $k$ (the number of events you're interested in)? That way, I can help you compute the probability accurately.