Two fair dice are tossed together once. (a) Draw a sample space for the possible outcomes ; (b) Find the probability of getting a total : (i) of 7 or 8 ; (ii) less than 4.
Explanation
(a)
1
2
3
4
5
6
1
1, 1
1, 2
1, 3
1, 4
1, 5
1, 6
2
2, 1
2, 2
2, 3
2, 4
2, 5
2, 6
3
3, 1
3, 2
3, 3
3, 4
3, 5
3, 6
4
4,1
4, 2
4, 3
4, 4
4, 5
4, 6
5
5, 1
5, 2
5, 3
5, 4
5, 5
5, 6
6
6, 1
6, 2
6, 3
6, 4
6, 5
6, 6
(b) (i) P(getting a total of 7) = \(\frac{6}{36}\) P(getting a total of 8) = \(\frac{5}{36}\) P(getting a total of 7 or 8) = \(\frac{6}{36} + \frac{5}{36}\) = \(\frac{11}{36}\) (ii) P(getting a total less than 4) = \(\frac{3}{36}\) = \(\frac{1}{12}\)
