Page 2 - Xl-CH-16-LESSON NOTE

Example : A die is thrown.

S = { 1, 2, 3, 4, 5, 6}

E = event of getting odd number.

E = {1, 3, 5}

TYPES OF EVENT:

Impossible Event

An event which contain no elements from sample space is called impossible event.

Example: getting 7 in a rolling die once is an impossible event.

SIMPLE EVENT “OR” ELEMENTARY EVENT :

An event E is called simple event or elementary event, if it has only one sample point of
the sample space.

For example: in the experiment of tossing two coins the sample is

S = {HH, HT, TH, TT}

E = event of getting both are head.

E ={ HH}

COMPOUND EVENT:

Any event having more than one sample point is called a compound event.
In experiment of tossing two coins, let

: Exactly one head = {HT, TH}
1

: Exactly one tail = {HT, TH}
2
: At least one tail = {TT, TH, HT}
3
: At most two heads = {TT, TH, HT, HH}
4

All these event contains more than one sample point so they are compound events.