Understanding Probability
This deep dive covers Understanding Probability within Basic Probability for GCSE Mathematics. Revise Basic Probability in Probability for GCSE Mathematics with 13 exam-style questions and 20 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 4 of 7 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 7
Practice
13 questions
Recall
20 flashcards
Understanding Probability
The Basic Formula
P(event) = Number of favourable outcomes / Total number of possible outcomes
Example 1: Coin Flip
A fair coin has 2 possible outcomes: heads or tails
- P(heads) = 1/2 = 0.5 = 50%
- P(tails) = 1/2 = 0.5 = 50%
Example 2: Rolling a Die
A standard die has 6 faces numbered 1, 2, 3, 4, 5, 6
- P(rolling a 3) = 1/6 ≈ 0.167 = 16.7%
- P(rolling an even number) = 3/6 = 1/2 = 0.5 = 50%
- P(rolling a number less than 7) = 6/6 = 1 = 100% (certain)
- P(rolling an 8) = 0/6 = 0 = 0% (impossible)
Example 3: Drawing Cards
A standard deck has 52 cards: 13 spades, 13 hearts, 13 diamonds, 13 clubs
- P(drawing a spade) = 13/52 = 1/4 = 0.25 = 25%
- P(drawing an ace) = 4/52 = 1/13 ≈ 0.077 = 7.7%
- P(drawing a red card) = 26/52 = 1/2 = 0.5 = 50%
Keep building this topic
Read this section alongside the surrounding pages in Basic Probability. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Basic Probability
Which value represents an impossible event on a probability scale?
Explain what is meant by theoretical probability and state the formula used to calculate it.
Quick Recall Flashcards
13 questions on Basic Probability — practise free
Instant marking, adaptive difficulty, and 20 spaced repetition flashcards. Free until your GCSEs.
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