**
Definition and basic properties
of probability
**

*
Axiomatic and classical
definitions of probability.
*

*
Probability of event.
Basic properties of probability.
*

**
**

**
The axiomatic definition of
probability.
**
Let a
space of elementary events

*E*be given and such single number

*Ð*(

*À*) corresponds to each event

*À*

*Å*, that:

Then we say, that the probability is
defined on events of
*
E
*
, and the number
*
Ð
*
(
*
À
*
) is called
**
the
probability of an event
**

*A*.

**
The classical definition of
probability
**
.

**Let a space of elementary events**

*E*be given and this space consists of

*N*equally likely elementary events, among which there are

*n*events, favorable for an event

*A*. Then the number

*
Ð
*
(
*
À
*
) =
*
n
*
*
/ N
*

is called
**
the probability of
an event
**

*A*.

**
Basic properties of
probability
**
. Let a
space of elementary events

*E*be given and probabilities

*P*are defined on events of

*E*. Then: