A red and a green dice are rolled.
What's the probability that the sum of the pips on the top face is 5 or showing number greater than 3 ?
This is usually the best way to do 2 dice questions - you will always see a pattern emerge.
There are 27 possibilities that have a number greater than 3 They are red.
There are 4 that add to 5 they are highlighted in yellow.
There are 2 that are in both groups. You do not want to add those twice.
So number of possibilities is 27+4 -2 = 29
So the probability that the sum of the pips on the top face is 5 or at least one of the numbers is greater than 3 is
\(\frac{29}{36}\)
| red | die | |||||
|---|---|---|---|---|---|---|
| green | 11 | 12 | 13 | 14 | 15 | 16 |
| die | 21 | 22 | 23 | 24 | 25 | 26 |
| 31 | 32 | 33 | 34 | 35 | 36 | |
| 41 | 42 | 43 | 44 | 45 | 46 | |
| 51 | 52 | 53 | 54 | 55 | 56 | |
| 61 | 62 | 63 | 64 | 65 | 66 |