Idea 6of 22Builds onProbability as a fraction
Impossible is 0, certain is 1
What are the smallest and biggest a probability can be?
Today you'll discover
- what a probability of 0 means
- what a probability of 1 means
- where every other probability goes
Think firstA spinner that is blue all over
A spinner is blue all over. What is the probability of landing on orange?
Decide first, then press Next. Look at the two ends of the line.
A line from 0 on the left to 1 on the right, cut into quarters. The word impossible appears under 0 and certain under 1; then pointers place orange on the all-blue spinner at 0 and blue at 1, and the quarter marks are labelled. The last step shows the line for a bag of 3 green marbles.
See the whole ideathe big idea and the key word, in one place
The big idea
A probability of 0 means impossible; 1 means certain; every other probability lies between.
The two ends
The line runs from never to always.
- impossible0
- certain1
For exampleRolling a 7 on a 1-to-6 number cube is impossible: 0. The sun rising tomorrow is certain: 1.
Key words
- probability line
- a line from 0 to 1 that shows how likely events are
- impossible
- can never happen; its probability is 0
- certain
- will always happen; its probability is 1
Ready to use it?
- Say whether an event is impossible or certain.
- Mark 0 and 1 on a probability line.