Answer
Probability is greater for 3 dices
Work Step by Step
Ways to get a total of 9 with 2 dice rolled = (3,6),(4,5),(5,4),(6,3) =4
Total possibilities with 2 dices = $6^{2}$= 36
Probability = 4/36 = 0.1111
Ways to get a total of 9 with 3 dice rolled = 25
Total possible outcomes with 3 dices = $6^{3}$ = 216
Probablity = 25/216= .1157
.1157>.1111
Hence the probability of getting a sum of 9 is more when 3 dices are rolled rather than 2.
