Many Consumer products, utilise reliability theory in the design of the Product in order to reduce the Probability of failure. The Failure of probability may be closely associated, with the product`s warranty. It is widely recognised that the term probability is something, which is used in the contexts, where it has nothing to do with Physical randomness. The theory of probability is one interpretation of the concept of probability. This kind of objective probability is sometimes also called `Chance`. The main challenge, facing probability theories, is to say exactly, what is meant. At present, unfortunately, none of the well-recognised accounts of propensity comes close to meet this challenge. This book is to encounter a very genuine need to obtain the information required, in order to reach the assumed Level of understanding.