Q(x) is a mathematical function often used in statistics and probability theory. It represents the tail probability of the standard normal distribution, which is a bell-shaped curve that describes how values are distributed around the mean. Specifically, Q(x) gives the probability that a standard normal random variable is greater than a certain value x. In practical terms, Q(x) helps in determining how extreme a value is in relation to the average. It is commonly used in fields such as finance, engineering, and social sciences to assess risks and make informed decisions based on statistical data.