Probability = number of favorable outcomes/number of total outcomes
The sample space for rolling two dice is shown below
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
The pair of numbers are the outcomes in the two dies for a given throw. From the table,
total number of outcomes = 36
a) The outcomes in which the sum is not less than 9 are 3,6 4,5 4,6 5,4 5,5 5,6 6,3 6,4 6,5 6,6
number of favorable outcomes = 10
Probability of rolling a sum not less than 9 = 10/36
Probability of rolling a sum not less than 9 = 5/18
b) The outcomes in which the sum is not more than 4 are 1,1 1,2 1,3 2,1 2,2 3,1
number of favorable outcomes = 6
Probability of rolling a sum not more than 4 = 6/36
Probability of rolling a sum not more than 4 = 1/6
c) The outcomes in which the sum is 6 or more are 1,5 1,6 2,4 2,5 2,6 3,3 3,4 3,5 3,6 4,2 4,3 4,4 4,5 4,6 5,1 5,2 5,3 5,4 5,5 5,6 6,1 6,2 6,3 6,4 6,5 6,6
number of favorable outcomes = 26
Probability of rolling a sum of 6 or more = 26/36
Probability of rolling a sum of 6 or more = 13/18