Question:
In a random experiment, a fair die is rolled until two fours are obtained in succession. The probability that the experiment will end in the fifth throw of the die is equal to:
Correct Option: , 2
Solution:
$\frac{1}{6^{2}}\left(\frac{5^{3}}{6^{3}}+\frac{2 C_{1} \cdot 5^{2}}{6^{3}}\right)=\frac{175}{6^{5}}$
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