# Introduction to Probability

In this chapter, we shall introduce the concept of probability as a measure of uncertainty.

In the Theory of Probability we deal with events, which are outcomes of an experiment. The word â€˜experimentâ€™ means an operation which can produce some well defined outcome(s). There are two types of experiments:

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(i) Deterministic

(ii) Random or Probabilistic.

# Deterministic Experiments

Deterministic experiments are those experiments, which when repeated under identical conditions produce the same result or outcome. When experiments in science and engineering are repeated under identical conditions, we obtain almost the same result every time.

# Random or Probabilistic Experiment

If an experiment, when repeated under identical conditions, does not produce the same outcome every time but the outcome in a trial is one of the several possible outcomes, then it is known as a random or probabilistic experiment. For example, in tossing of a coin one is not sure if a head or a tail will be obtained, so it is a random experiment. Similarly, rolling an unbiased die and drawing a card from a well-shuffled pack of cards are examples of a random experiment.