Q.

If an unbiased dice is rolled thrice, then the probability of getting a greater number in the ith roll than the number obtained in the (i-1)th roll, i=2,3, is equal to           [2024]

1 554  
2 254  
3 154  
4 354  

Ans.

(1)

Let X be the event of getting a greater number than the previous one in a throw of a die.

Favourable outcomes to X=C36

[ C36 are ways of getting 3 outcomes one less than other as we have total 6 possible outcomes]

Total outcomes = 63

P(X)=C3663=20216=554