What is the probability of two independent events?

P(A and B) = P(A) × P(B). For example, two heads in a row = 0.5 × 0.5 = 0.25 (25%).

What is the complement rule?

P(not A) = 1 - P(A). If probability of rain is 30%, probability of no rain is 70%.

Probability Formula

Probability measures the likelihood of an event occurring. It ranges from 0 (impossible) to 1 (certain). Understanding probability helps in decision-making and risk assessment.

Basic Probability Formula

P(A) = Number of Favorable Outcomes / Total Number of Outcomes

Where:

P(A) = Probability of event A
Favorable = Outcomes where A occurs
Total = All possible outcomes

Step-by-Step:

1
Count favorable outcomes
How many ways can your desired event happen?
2
Count total outcomes
How many total possible outcomes exist?
3
Divide
Favorable / Total = Probability (between 0 and 1).

Worked Examples:

Rolling a die

Event: Getting a 6

Result: 1/6 = 16.7%

1 favorable outcome (6) out of 6 total outcomes.

Drawing a heart

Event: Heart from deck

Result: 13/52 = 25%

13 hearts in a 52-card deck.