Probability tells how likely an event is going to happen
How to write or represent probability?
P(event) = percentage
Eg: fair coin for events, P(Head) = 0.5 = P(Tail)
Note:
Sum of all events is always equal to 100% ie, 1
P(Head) + P(Tail) = 0.5 + 0.5 = 1 = 100%
Example:
If a mean of data set is 10 and data is normally distributed, then P(10) = 0.5. so if a person is randomly picked from the data set his score will 10 at 50% chance
Probability of event:
P(Event) = Number of event we are interested in/ Number of all possible event
Eg:
P(Head) = ½ = 0.5 = 50%
Probability of combination of events:
To combine multiple event we use or function, that is simply addition of events
P(event ) = P( a or b or c or d)
P9event) = P(a) + P(b) + P(c) + P(d)
Example:
If 2 fair coins are tossed simultaneously,
| Sl No | Coin 1 possibilities | Coin2 possibilities |
| 1 | Head | Head |
| 2 | Head | Tail |
| 3 | Tail | Head |
| 4 | Tail | Tail |
P(Heads at least once) = P( Head and Head) + P(Head and Tail) + P (Tail and Head) / P(all possible occurrences)
P(Heads at least once) = (1+1+1) / 4 = ¾ =0.75 = 75%
