Elementary Event
An elementary event is an event that contains exactly one single outcome of a random experiment. It is the most basic type of event in probability and cannot be broken down into simpler sub-events.
Key Concepts
In any random experiment, an elementary event represents just one specific result from the entire sample space.
If an event consists of more than one outcome, it is classified as a compound event rather than an elementary event.
A fundamental rule in probability states that the sum of the probabilities of all possible elementary events of an experiment is always exactly 1.
Formula & Equation
P(E_i) represents the probability of the i-th elementary event, and n is the total number of elementary events in the sample space.
Common Misconceptions
Myth: Getting an even number when rolling a die is considered an elementary event.
Fact: Getting an even number is a compound event because it includes three distinct outcomes (2, 4, and 6). An elementary event must have exactly one outcome, such as rolling a 2.
Real World Applications
When tossing a standard coin, getting a Tail is an elementary event because it is a single, distinct outcome.
When rolling a standard six-sided die, getting a 5 is an elementary event, as it corresponds to exactly one outcome in the sample space.
Frequently Asked Questions
What is the sum of probabilities of all elementary events of an experiment?
The sum of the probabilities of all possible elementary events of a random experiment is always equal to 1.
What is the difference between an elementary event and a compound event?
An elementary event has exactly one outcome, while a compound event contains two or more outcomes from the sample space.