Brainlag Plus
Brainlag PlusSample spaces and combined events
List outcomes systematically, count with the product rule, and use sample spaces for games, codes, cards without replacement and three picks.
Sample space grids
When two things happen together, list every combination in a grid. Each cell is one equally likely outcome, so count cells, not different totals.
- spinner A: 1, 3, 5; spinner B: 2, 4
- outcomes: 3 × 2 = 6
- totals: 3, 5, 5, 7, 7, 9
- P(total greater than 5) = 3/6 = 1/2
A game is fair when each player has the same chance of winning. With two spinners numbered 1 to 4, an odd product needs both numbers odd: 2 × 2 = 4 of the 16 outcomes. The player who wins on odd has probability 4/16 = 1/4, so the game is not fair.
The rest of this lesson and its 8 practice questions are in Plus.
Screen 1 of 4, free to read.
- 8 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards