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Intermediate 📊 Probability & Statistics Topic 32 of 98

Basic Probability

Favourable outcomes over total equally likely outcomes.

Key idea

Favourable outcomes over total equally likely outcomes.

In depth

For equally likely outcomes, P(E) = (favourable outcomes)/(total outcomes). Probabilities are between 0 and 1, and the probabilities over the entire sample space sum to 1.

Worked example

P(rolling an even number) = 3/6 = 1/2.

Formula

P(A) = n(A)/n(S)

Real-world uses

Common mistake

Applying the formula when outcomes are not equally likely.

How to learn this

  1. Read the key idea and say it in your own words.
  2. Work through the worked example, then try a similar problem.
  3. Use the interactive lesson’s visual and mini-quiz to check the pattern.

Frequently asked questions

What is Basic Probability?

Favourable outcomes over total equally likely outcomes. It is a topic at the intermediate level in Probability & Statistics.

What is the formula for Basic Probability?

The key formula is P(A) = n(A)/n(S).

Where is Basic Probability used in real life?

Real-world examples: Estimating the chance of rain, winning a raffle or drawing a red card.

What should I learn before Basic Probability?

Make sure you are comfortable with Sample Space and Events, the previous topic in Probability & Statistics.

What is a common mistake with Basic Probability?

Applying the formula when outcomes are not equally likely.

How can I practise Basic Probability?

Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.

What comes after Basic Probability?

Move on to Probability Scale next.

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