In a multiple-choice question, there are five alternative answers, of which one or more than one are correct. A candidate will get marks on the question if he ticks all the correct answers. So he deci

Question

In a multiple-choice question, there are five alternative answers, of which one or more than one are correct. A candidate will get marks on the question if he ticks all the correct answers. So he decides to tick answers at random, if the least number of chances , he should be allowed so that the probability of his getting marks on the question exceeds $1/8$ is $K$ , then $K =$

(the student always attempt the question)

TestHub · Accepted Answer

The probability that he get marks = 31 1 ​ The probability that he get marks in second trial is 31 30 ​ × 30 1 ​ = 31 1 ​ The probability that he get marks in third trial is 31 1 ​ Continuing this process the probability from r trial is 31 r ​ > 8 1 ​ ​ ⇒ r > 8 31 ​ ​ r = 4 ​

Mathematics - Probability Question with Solution | TestHub

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