Question : A die is rolled 4 times. The probability of getting a larger number than the previous number each time is
(A) 17/216
(B) 5/432
(C) 15/432
(D) none of these
Answer : option (B)
Solution :
Given that, n(S) = 6 × 6 × 6 × 6 = 6^{4}
The number of favourable ways is 6C_{4}=\dfrac{6\times 5}{2}=15
therefore, the required probability is,
\dfrac{15}{6\times 216}-\dfrac{5}{2\times 216}\Rightarrow \dfrac{5}{432}