# Favourable Elementary Events

An elementary event is said to be favourable to a compound event A, if it satisfies the definition of the compound event A.

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In other words, an elementary event E is favourable to a compound event A, if we say that the event A occurs when E is an outcome of a trial.

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Consider the random experiment of throwing a pair of dice and the compound event A defined by "Getting 8 as the sum". We observe that the event A occurs if we get any one of the following elementary events as outcome:

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(2, 6)

(6, 2)

(3, 5)

(5, 3)

(4, 4)

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So, there are 5 elementary events favourable to event A.

If two coins are tossed simultaneously and A is an event associated to it defined as "getting exactly one head". We say that the event A occurs if we get either HT or TH as an outcome. So, there are two elementary events favorable to the event A.