Tag: Experimental probability

What is Experimental probability?

This is a probability that has been determined from experience or experiments. It involves determination of chances from results of previous tests being conducted.

Each test is called a trial and the possible results of a trail is called an outcome. The general experimental probability of a result is given by:

Range of Probability

here are a few things to note about probability:

1. The greater the probability value, the more likely an event is likely to occur
2. The probability of an event A which is certain to occur is 1or 100% and can be written as P(A) = 1.
3. The probability of an event A which is i impossible to occur is zero. and can be represented as p(A)=0. For example the probability of days going backward to last year is zero.
4. The probability of any event A lies between 0 and 1 inclusively hence the probability of any event occurring can be expressed as 0 ≤ P(A) ≤ 1.
5. If P(A) is the probability of an event A happening and P(A’) is the probability of an event A not happening, then P(A’) = 1- P(A) and P(A’) + P(A) = 1.
6. probabilities are usually expressed as fractions, decimals or percentages.

Possibility space

This is the list of all possible outcomes also referred to as a sample space or a probability space.

Theoretical probability

This is the probability of the events that can be calculated without necessarily using any experience or doing any experiment.

Mutually exclusive events

This are events in which occurrence of one event excludes the occurrence of the other event.

If A and B are two mutually exclusive events, then P(A or B) = P(A) + P(B).

For example when a coin is tossed once, head and tail have each the same chances of occurring. The probabilities of mutually exclusive events adds up to 1.

P(tail) = 1/2 and p(head) = 1/2

hence P(head or tail) = P(head) + P(tail) = 1/2 + 1/2 = 1

Independent Events

This are events which occurrence of one event does not affect occurrence of the other event.

if two events A and B are independent events, the probability of them occurring together is the product of their individual probabilities.

i.e. P( A and B) = P(A) x P(B)

---