We know that, Prime numbers =2,3,5 Composite numbers =4,6. Pairs of prime numbers on both the die in first throw ={(2,2),(2,3),(2,5),(3,2),(3,3),(3,5), (5,2),(5,3),(5,5)} ⇒ Total pairs =9 Pairs of composite numbers on both the die in second throw ={(4,6),(4,4),(6,4),(6,6)} ∴ Required probability =