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A multiple choice emamination has 5 questions. Each question has three alternative answers of which exactly one is correct. The probability that a student will get 4 or more correct answers just guessing isA. `(17)/(3^(5))`B. `(13)/(3^(5))`C. `(11)/(3^(5))`D. `(10)/(3^(5))` |
Answer» Correct Answer - C Answer for any question can be guessed in 3 ways. `therefore` Probability that any question is correct `=1/3` From five questions if at least four questions are correctly answered then required probability = Probability that four questins are correctly answered + Probability that five questions are correctly answered `=""^(5)C_(4)((1)/(3))^(4)((2)/(3))+""^(5)C_(5)((1)/(3))^(5)=(11)/(3^(5))` |
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