The total number for the sample space for two cubes rolled is 36
1,1; 1,2....; 1,6
2,1; 2,2..; 2,6
. .
. .
6,1; 6,2...; 6,6
Event A (less than 10; 1 - 9)
(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)
(5,1); (5,2); (5,3); (5,4)
(6,1); (6,2); (6,3)
The sample space has 30 elements
P (A) = 0.83
Event B (sum of numbers on both cubes is a multiple of 3)
Event A already happened, we have Event B as:
(1,2); (1,5)
(2,1); (2,4)
(3,3); (3,6)
(4,2); (4,5)
(5,1); (5,4)
(6,3)
The sample space has 11 elements
P (B|A) = 0.37