Idea 4of 22Builds onProbability as a fraction
Every section goes on the bottom
What if the colour you want is in several places?
Today you'll discover
- how to count a colour in several sections
- what the bottom always counts
- how the same works for marbles
Think firstEight equal sections; orange is in three places
What is the probability of landing on orange?
Decide first, then press Next. Count every section for the bottom.
A spinner of eight equal sections, three orange and five blue, mixed round the circle. The sections are numbered 1 to 8; then the three orange sections are outlined; then orange 3/8 and not orange 5/8 are written beside it. The last step shows a jar of 2 orange, 3 green and 5 blue marbles.
See the whole ideathe big idea and the key word, in one place
The big idea
Count every favourable outcome for the top, and every outcome, wanted or not, for the bottom.
Compare them3 orange to 5 blue compares the colours with each other. 3 orange out of 8 sections is the probability: 3/8.
Easy to get wrongA bag of 3 colours is not 1/3 each unless each colour has the same number of marbles.
Key word
- favourable outcome
- an outcome that makes the event you want happen
Ready to use it?
- Find a probability when a colour is in several sections.
- Find the probability of a colour of marble in a bag.