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InterviewSolution
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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 toA. `(175)/(6^(6))`B. `(225)/(6^(5))`C. `(200)/(6^(5))`D. `(150)/(6^(5))` |
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Answer» Correct Answer - A Since, the experiment should be end in the fifth throw of the die, so total number of outcomes are `6^5` Now, as the last two throws should be result in two fours `""/(i)""/(ii)""/(iii)4/(iv)4/(v)` So, the third throw can be l , 2, 3, 5 or 6 (not 4). Also, throw number (i) and (ii) can not take two fours in succession, therefore number of possibililites for throw `(i) and (ii) =6^2-1=35 [therefore ` when a pair of dice is thrown then (4,4) occur only once ] Hence , the required probility `=(5xx35)/6^5=(175)/6^5` |
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