# Compound, Complex, Composite, Elementary, Simple, Events - Probability

# Composite or Compound Events

These events can be viewed as a union of two or more smaller events.

## Examples

In the experiment of throwing a die:

**The Event of getting an even number is a Composite Event**This event can be further sub-divided or broken down into 3 simpler events

- the event of getting 2,
- the event of getting 4 and
- the event of getting 6

Occurrence of any one of these events

⇒ Occurrence of the event of getting an even number.

In the experiment of throwing a die:

**The Event of getting a number divisible by three is a composite event**This event can be further sub-divided or broken down into two simpler events,

- the event of getting 3 and
- the event of getting 6

Occurrence of any one of these events

⇒ Occurrence of the event of getting a number divisible by 3.

In the experiment of drawing a token from a bag containing 20 tokens numbered from 1 to 20:

**The Event of drawing a token with a number which is a multiple of 5 is a composite event**This event can be further sub-divided or broken down into 4 simpler events,

- the event of drawing a token with the number 5 on it
- the event of drawing a token with the number 10 on it
- the event of drawing a token with the number 15 on it and
- the event of drawing a token with the number 20 on it

Occurrence of any one of these events

⇒ Occurrence of the event of drawing a token with a number which is a multiple of 5.

# Elementary or Simple Events

## Examples

In the experiment of tossing a coin:

**The Event of getting a HEAD is an Elementary Event**This event cannot be further sub-divided or broken down into simpler events.

**The Event of getting a TAIL is an Elementary Event**This event cannot be further sub-divided or broken down into simpler events.

In the experiment of rolling a die:

**The Event of getting ONE on the die is an Elementary Event.****The Event of getting TWO on the die is an Elementary Event.**- ...
- ...
- ...
**The Event of getting SIX on the die is an Elementary Event.**

In the experiment of drawing a token from a bag containing 20 tokens numbered from 1 to 20:

**The Event of drawing a token with the number ONE on it is an Elementary Event.****The Event of drawing a token with the number TWO on it is an Elementary Event.**- ...
- ...
- ...
**The Event of drawing a token with the number NINE TEEN on it is an Elementary Event.****The Event of drawing a token with the number TWENTY on it is an Elementary Event.**

Therefore, we can say that compound events can be broken down into two or more elementary events. The compound event occurs when any one of these elementary events occur.