Question

If A denotes some​ event, what does Upper A overbar ​denote? If ​P(A)equals0.008​, what is the value of ​P(Upper A overbar​)? If ​P(A)equals0.008​, is Upper A overbar ​unlikely? What does Upper A overbar ​denote?

Answer 1

The symbol represents the complement of an event A.

The complement of an event is the set of all possible outcomes except that particular event A.

For example, if 'A' is the event of getting heads on tossing a coin, then its complement would represent getting tails.

Another example would be: If 'A' is the event of getting '6' on rolling a fair die then is the event that the outcome is anything (out of 1,2,3,4,5) but 6.

Thus, according to total probability sum law -

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Thus, if P(A) = 0.008 then -

As this is a very high probability value so its not unlikely. Instead its very likely.

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We can say that probability of occurence of any event rather than A is 0.992.

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