Sum is a prime number i.e. the sum of the dice outcomes can be 2, 3,5,7,11.
These sums are shown in following pairs
(1,1), (1,2), (2, 3), (3, 4), (5, 6)
(5, 2), (4,1), (2,1), (4, 3), (6, 5)
(2, 5), (1,4), (3, 2), (1,6), (6,1)
∴ Required probability
== [2 dice
=6×6=36]