Probability Basics

Understanding chance, likelihood, and uncertainty

What is Probability?

Probability is the measure of the likelihood that an event will occur. It is quantified as a number between 0 and 1, where 0 indicates impossibility and 1 indicates certainty.

0 (Impossible) 0.5 (Even Chance) 1 (Certain)

P(Event) = Number of favorable outcomes / Total number of possible outcomes

Basic Probability Concepts

Experiment: A process that produces an outcome (e.g., rolling a die)

Outcome: A possible result of an experiment (e.g., rolling a 4)

Sample Space: The set of all possible outcomes (e.g., {1, 2, 3, 4, 5, 6} for a die)

Event: A set of outcomes (e.g., rolling an even number)

Example: Coin Toss

When flipping a fair coin:

Sample Space = {Heads, Tails}

P(Heads) = 1/2 = 0.5

P(Tails) = 1/2 = 0.5

Probability Rules

Rule 1: The probability of an impossible event is 0

Rule 2: The probability of a certain event is 1

Rule 3: The probability of any event is between 0 and 1

Rule 4: The sum of probabilities of all possible outcomes is 1

Rule 5: P(not A) = 1 - P(A)

Coin Flip Simulation

Click the button to flip a coin and see the results:

H

T

Results:

Heads: 0/0

Tails: 0/0

P(Heads) = 0

P(Tails) = 0

Dice Roll Simulation

Click the button to roll a die and see the results:

1

?

Results:

1

2

3

4

5

6

Total Rolls: 0

Probability Calculator

Calculate the probability of an event:

Number of favorable outcomes:

Total number of possible outcomes:

Result:

P(Event) = 0

Percentage: 0%

Probability Basics | Mathematics Learning Resource