When two events occur, there are several possible outcomes.

For example, when these two spinners are spun, there are 4 x 4 = 16 possible outcomes.

The two scores are added together and so we can create a Sample-Space diagram to show the possible totals.

1 | 2 | 3 | 4 | |
---|---|---|---|---|

1 | 2 | 3 | 4 | 5 |

2 | 3 | 4 | 5 | 6 |

3 | 4 | 5 | 6 | 7 |

4 | 5 | 6 | 7 | 8 |

The possible totals are 2, 3, 4, 5, 6, 7 and 8.

The probability of getting a total of 7, P(7) = 2/16 = 1/8