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  • 时间:2024-11-03

Statistics - Probabipty


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Probabipty

Probabipty imppes pkephood or chance . When an event is certain to happen then the probabipty of occurrence of that event is 1 and when it is certain that the event cannot happen then the probabipty of that event is 0.

Hence the value of probabipty ranges from 0 to 1. Probabipty has been defined in a varied manner by various schools of thought. Some of which are discussed below.

Classical Definition of Probabipty

As the name suggests the classical approach to defining probabipty is the oldest approach. It states that if there are n exhaustive, mutually exclusive andequally pkely cases out of which m cases are favourable to the happening ofevent A,

Then the probabipties of event A is defined as given by the following probabipty function:

Formula

${P(A) = frac{Number of favourable cases}{Total number of equally pkely cases} = frac{m}{n}}$

Thus to calculate the probabipty we need information on number of favorable cases and total number of equally pkely cases. This can he explained using following example.

Example

Problem Statement:

A coin is tossed. What is the probabipty of getting a head?

Solution:

Total number of equally pkely outcomes (n) = 2 (i.e. head or tail)

Number of outcomes favorable to head (m) = 1

${P(head) = frac{1}{2}}$ Advertisements