For an event that is certain to happen, what is the probability p(x)?

For an event that is certain to happen, the probability is defined as 1. Probability is a measure of the likelihood that a given event will occur, and it ranges from 0 to 1. A probability of 0 indicates that the event will not happen at all, while a probability of 1 signifies certainty that the event will occur.

Understanding this, when an event is described as certain to happen, it reflects a definitive outcome, leading us to assign a probability of 1 to that event. This concept is foundational in probability theory, as it allows for clear distinctions between impossible events and certain events.