Final answer:
The subject of this question is Mathematics, specifically the concept of the Poisson distribution and its application to the arrivals at a walk-in optician's in a shopping center.
Step-by-step explanation:
The subject of this question is Mathematics. Specifically, it involves the concept of the Poisson distribution.
A Poisson distribution is used to model the number of events that occur in a fixed interval of time or space. It is characterized by a mean, which represents the average rate at which the events occur.
In this case, the arrivals at a walk-in optician's in a shopping center are Poisson distributed with a mean of 3.4.