Q.

Three dice are rolled. If the probability of getting different numbers on the three dice is pq, where p and q are co-prime, then qp is equal to          [2023]

1 4  
2 3  
3 1  
4 2  

Ans.

(1)

If numbers are different on all three dice,

Total number of favourable outcomes =6×5×4=120

Total number of possible outcomes =63=216

  Required probability=120216=59=pq

So, q-p=9-5=4