a. probability that the sum of the two numbers is 6:
Possible rolls with sums of 6 are: (1,5); (2,4); (3,3); (4,2); (5,1).
Total number of possible outcomes for rolling 2 fair 6-sided dice: 36
Hence:
[tex]P=\frac{5}{36}[/tex]b. probability that the sum of the two numbers is 11:
Possible rolls with sums of 11 are: (5, 6); (6, 5).
Total number of possible outcomes for rolling 2 fair 6-sided dice: 36
Hence:
[tex]P=\frac{2}{36}[/tex]c. probability that the sum of the two numbers is 6 or 11:
[tex]P=\frac{5}{36}+\frac{2}{36}=\frac{7}{36}[/tex]