Idea 10of 22Builds onPut a probability on the line
Which spinner gives the better chance?
How do you compare chances on two different spinners?
Today you'll discover
- why the biggest section can mislead
- how to give both the same bottom
- how to choose
Think firstYou win on orange
You win on orange. Which spinner gives you the better chance?
Decide first, then press Next. Compare the whole of each colour, not one section.
Two spinners side by side. Spinner A has 8 equal sections, 3 orange; spinner B has 4, 1 orange. The sections are counted, the orange ones outlined, then the fractions 3/8 and 1/4 are written under them, and the line under both reads 3/8 and 1/4 = 2/8: spinner A is more likely. The last step shows spinners C and D for green.
See the whole ideathe big idea and the key word, in one place
The big idea
To compare two chances, write both with the same bottom; the bigger top is more likely.
Compare themOne big section against three small ones: count how much of the whole each colour covers, not the size of one section.
Easy to get wrongFractions with different bottoms cannot be compared by their tops. Change 1/4 to 2/8 first.
Key word
- more likely
- has a bigger probability, so it happens more often over many tries
Ready to use it?
- Compare the chance of a colour on two spinners.
- Choose the spinner that gives the better chance.