Probability of Single Events
Use the probability scale, calculate the probability of single events, and use the fact that probabilities sum to 1.
Overview
Probability measures how likely something is to happen, on a scale from 0 (impossible) to 1 (certain). In Year 8 students calculate the probability of single events — such as rolling a particular number on a dice — write probabilities as fractions, decimals or percentages, and use the idea that the probabilities of all outcomes add up to 1. This is the foundation for all the data and risk work that follows.
What You Will Learn
- Place events on a probability scale from 0 to 1
- Calculate the probability of a single event using equally likely outcomes
- Write probabilities as fractions, decimals or percentages
- Use the fact that the probabilities of all outcomes add up to 1
- Find the probability of an event not happening
Key Vocabulary
Common Mistakes to Avoid
- Writing a probability greater than 1 or as a whole number like 6
- Counting the total number of outcomes incorrectly
- Confusing the probability of an event with the probability of it not happening
- Not simplifying a probability fraction, or mixing up the numerator and denominator
What Comes Next
In Year 9 and at IGCSE this develops into the probability of combined events, sample space diagrams and tree diagrams, forming the IGCSE Probability topic.
Frequently Asked Questions
Can a probability ever be more than 1?
No. A probability is always between 0 and 1, where 0 means impossible and 1 means certain. If you get an answer above 1, you have made a mistake — usually by miscounting the total number of outcomes.
How do I find the probability that something does not happen?
Because all probabilities add up to 1, subtract the probability that it does happen from 1. If the probability of rain is 0.3, the probability of no rain is 1 − 0.3 = 0.7.
Study This Topic
Topic Details
- Stage
- Year 8
- Strand
- Statistics and Probability
- Framework ref
- 8Sp
- Difficulty
- Low
Build strong foundations in Probability of Single Events
A free trial class with Teacher Rig helps your Year 8 child master Probability of Single Events now — so IGCSE Maths feels familiar, not frightening, later.
Heading toward IGCSE? See how Probability of Single Events develops in IGCSE Probability (Cambridge 0580) →