Two fair dice are thrown together two times. Find the probability of obtaining a sum of seven in the first throw and a sum of four in the second throw.
Explanation
| + | 1 | 2 | 3 | 4 | 5 | 6 |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| 5 | 6 | 7 | 8 | 9 | 10 | 11 |
| 6 | 7 | 8 | 9 | 10 | 11 | 12 |
P(a sum of 7) = (frac{6}{36}) and P(a sum of 4) = (frac{3}{36})
P(a sum of 4) = (frac{3}{36})
P(a sum of 7 and a sum of 4) = (frac{6}{36} times frac{3}{36}) = (frac{1}{72})