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Question: Answered & Verified by Expert
In an examination, there are 3 multiple choice questions and each question has 4 choices. If a student randomly selects answer for all the 3 questions, what is the probability that the student will not answer all the 3 questions correctly?
MathematicsProbabilityNDANDA 2011 (Phase 1)
Options:
  • A $1 / 64$
  • B $63 / 64$
  • C $1 / 12$
  • D $11 / 12$
Solution:
2597 Upvotes Verified Answer
The correct answer is: $63 / 64$
Since, probability of answering all the three questions correctly $=\frac{1}{4} \times \frac{1}{4} \times \frac{1}{4}=\frac{1}{64}$
$\therefore$ Probability of not answering all the three questions correctly $=1-\frac{1}{64}=\frac{63}{64}$

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