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Probability

Two spinners, one grid

Spinner A has 4 equal parts: 1, 2, 3, 4. Spinner B has 3 equal parts: 1, 2, 3. Spin both together. You win if the numbers match. A grid is a table of boxes. Each box is a cell.

Spinner A across the top. Spinner B down the side.
Step 1 of 4
  1. Spinner A across the top. Spinner B down the side.
  2. Each A number pairs with each B number. 4 × 3 = 12 cells.
  3. The numbers match in 3 cells: (1, 1), (2, 2), (3, 3).
  4. Chance of a match = 3/12 = 1/4.

Write A first, then B

One result is a pair, like (2, 3). It means A shows 2 and B shows 3. (3, 2) means A shows 3 and B shows 2.

  • Ordered pair — two numbers written in a fixed order.
  • (2, 3) and (3, 2) are different results. Order matters.
  • Each cell is one outcome. All 12 cells are equally likely.
  • Both spinners have equal parts. So every pair has the same chance.

"A is bigger" means A's number is bigger than B's.

Same grid, more questions
QuestionCellsChance
numbers match(1, 1), (2, 2), (3, 3)3/12 = 1/4
A is bigger(2, 1), (3, 1), (3, 2), (4, 1), (4, 2), (4, 3)6/12 = 1/2
sum is 5(2, 3), (3, 2), (4, 1)3/12 = 1/4

Now try it. Tap every cell that fits the question. Then read the chance.

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This track

  1. 0 Start here
  2. 1 Chance = wanted ÷ all
  3. 2 Two spinners, one grid
  4. 3 Two dice, 36 pairs
  5. 4 0, 1, or in between
  6. 5 Count the slips, not the numbers
  7. 6 "Not" means 1 minus
  8. 7 "Or" means count each one once
  9. 8 All together, step by step
  10. 9 Coins: list every result
  11. 10 A pack of 52 cards
  12. 11 Words that pick numbers
  13. 12 One taken out, not put back
  14. 13 Checkpoint: coins, cards, numbers and draws
  15. 14 The big picture
  16. 15 Track quiz

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