Final Answer:

Step-by-step explanation:
The probability mass function (PMF) for a Poisson distribution is given by
is the mean of the distribution. In this case,
and we want to find
. Substituting the values, we get:
![\[ P(\mathrm{x}=2) = (e^(-1.9) \cdot 1.9^2)/(2!) \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/hy8dcvt1425n0o4u6uvo0fq0qpzsr3hm09.png)
Calculating this expression yields the final probability. Utilizing the exponential function, factorial, and the given mean, the calculation provides

Poisson distributions are often used to model the number of events occurring in a fixed interval of time or space. In this context,
represents the probability of observing exactly 2 events when the mean rate is 1.9. This probability is obtained by considering the likelihood of observing a specific number of events in a Poisson process. The formula encapsulates the balance between the rate of occurrence
and the specific outcome k, providing a precise probability for the given scenario.