Artificial Intelligence
Probability
Probability is about how Likely something is.
Probability is a Number between 0 and 1.
Probability is about how likely something is to occur, or how likely something is true.
The mathematic probability is a number between 0 and 1, where 0 indicates impossibility and 1 indicates certainty.
The probability of an event is:
The Number of ways it can happen / The number of possible outcomes.
Probability = Ways / Outcomes
Tossing Coins
When tossing a coin, there are two possible outcomes:
| Heads | Probability is 0.5 |
| Tails | Probability is 0.5 |
1 possibility (Heads) / 2 outcomes (Heads / Tails) = 1/2 = 0.5
P(A) - The Probability
The probability of an event A is often written as P(A).
When tossing two coins, there are 4 possible outcomes:
| Event | P(A) |
|---|---|
| Heads + Heads | 0.25 |
| Tails + Tails | 0.25 |
| Heads + Tails | 0.25 |
| Tails + Heads | 0.25 |
1 possibility (Heads + Heads) / 4 outcomes = 1/4 = 0.25
Throwing Dices
When throwing a dice, there are 6 possible outcomes:
| Event | P(A) |
|---|---|
| Lands on 1 | 0.1666666... |
| Lands on 2 | 0.1666666... |
| Lands on 3 | 0.1666666... |
| Lands on 4 | 0.1666666... |
| Lands on 5 | 0.1666666... |
| Lands on 6 | 0.1666666... |
1 Possibility: Lands on 1 / 6 outcomes = 1/6 = 0.1666666...
P(A) = P(B)
| P(A) = P(B) | Events A and B have the same chance to occur. |
| P(A) > P(B) | the event A has a higher chance to occur. |
| P(A) < P(B) | the event A has a lower chance to occur. |
Choosing a King
The probability of choosing a king in a deck of cards is 4 in 52.
Number of ways it can happen are 4 (there are 4 kings).
Number of outcomes are 52 (there are 52 cards).
The probability is 4 out of 52: 4/52 = 0.076923...
The probability is written P(king) = 0.076923.
Probability = Ways / Outcomes
6 Balls
I have 6 balls in a bag: 3 reds, 2 are green, and 1 is blue.
Blindfolded. What is the probability that I pick a green one?
Number of ways it can happen are 2 (there are 2 greens).
Number of outcomes are 6 (there are 6 balls).
The probability is 2 out of 6: 2/6 = 0.333333...
The probability is written P(red) = 0.333333.
Probability = Ways / Outcomes
