SOLUTION: Consider Experiment of rolling a pair of six-sided dice. Suppose we are interested in the sum of values showing on the dice: a) How many sample points are possible? b) What is the

Here are all possible rolls of a pair of six-sided dice:

(1,1) (1,2) (1,3) (1,4) (1,5) (1,6)
(2,1) (2,2) (2,3) (2,4) (2,5) (2,6) 
(3,1) (3,2) (3,3) (3,4) (3,5) (3,6) 
(4,1) (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) 

Count them.  I count 36. 

Let's color those red with sum 7:

(1,1) (1,2) (1,3) (1,4) (1,5) (1,6)
(2,1) (2,2) (2,3) (2,4) (2,5) (2,6) 
(3,1) (3,2) (3,3) (3,4) (3,5) (3,6) 
(4,1) (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)

Count the red ones.  I count 6. That's a probability of 6 out of 36,
or 6/36, which reduces to 1/6.

Let's color those red with sum 9 or greater:

(1,1) (1,2) (1,3) (1,4) (1,5) (1,6)
(2,1) (2,2) (2,3) (2,4) (2,5) (2,6) 
(3,1) (3,2) (3,3) (3,4) (3,5) (3,6) 
(4,1) (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)

Count the red ones.  I count 10. That's a probability of 10 out of 36,
or 10/36, which reduces to 5/18.

Edwin