Given,
A= Event that sum of the numbers appearing is 4 appearing is 4
={(1,3),(2,2),(3,1)} and
B= Event that 3 appears at least once
={(3,1),(3,2),(3,3),(3,4),(3,5),(3,6),(1,3),(2,3),(4,3),(5,3),(6,3)}
A∩B={(1,3),(3,1)} ⇒‌‌n(A∩B)=2 ∴‌‌P(A/B)=‌=‌=‌