Question

Three dice are rolled. If the probability of getting different numbers on the three dice is p/q , where p and q are co-prime, then q – p is equal to

(1) 4 

(2) 3 

(3) 1 

(4) 2

Answer 1

Correct option is (1) 4 

Total number of ways = 6³ = 216 

Favourable outcomes ⁶p₃ = 120

⇒ Probability = 120/216 = 5/9

⇒ p = 5,q 9 

⇒ q - p = 4