The probability of an impossible event (P(A)) is equal to what value?

The probability of an impossible event is defined as 0. This is because probability is a measure of the likelihood of an event occurring, where the range of probabilities is defined from 0 to 1. A probability of 0 indicates that the event cannot happen at all, which is precisely the case for an impossible event.

In the context of probability, if an event is impossible, it doesn't occur in any possible outcome of the experiment, thus leading to a probability measurement of 0. The other values listed do not represent the probability of an impossible event; a probability of 1 would imply certainty that an event will occur, while a probability of 0.5 suggests that an event is as likely to occur as not occur. A negative probability, such as -1, is not a valid concept within the standard framework of probability. Therefore, a probability of 0 is indeed the correct and accurate measurement for an impossible event.