JEE MainMathematicsProbabilityMCQ+4 / −1
If the numbers appeared on the two throws of a fair six faced die are and , then the probability that , for all , is :
- A
- B
- C
- D
View written solutionFree
Correct answer: A
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We need the quadratic to satisfy
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For a quadratic to be positive for all real , we need:
- , and
- discriminant .
Here, , so we only need That is,
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Since and are outcomes of two throws of a fair die, Total number of ordered pairs is
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Count pairs satisfying We check each possible value of :
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If : true for all . Count .
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If : so . Count .
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If : so . Count .
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If : so . Count .
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If : impossible. Count .
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If : impossible. Count .
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Total favorable cases:
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Therefore, the required probability is
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Comparing with the stored correct answer: stored answer is A, i.e. , which matches.
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