Medium MCQ +4 / -1 PYQ · JEE Mains 2021

Let a computer program generate only the digits 0 and 1 to form a string of binary numbers with probability of occurrence of 0 at even places be ${1 \over 2}$ and probability of occurrence of 0 at the odd place be ${1 \over 3}$. Then the probability that '10' is followed by '01' is equal to :

  1. A ${1 \over 18}$
  2. B ${1 \over 3}$
  3. C ${1 \over 9}$ Correct answer
  4. D ${1 \over 6}$

Solution

P(0 at even place) = ${1 \over 2}$ <br><br>P(0 at odd place) = ${1 \over 3}$ <br><br> P(1 at even place) = ${1 \over 2}$ <br><br>P(1 at odd place) = ${2 \over 3}$ <br><br>P(10 is followed by 01) <br><br>= $$\left( {{2 \over 3} \times {1 \over 2} \times {1 \over 3} \times {1 \over 2}} \right) + \left( {{1 \over 2} \times {1 \over 3} \times {1 \over 2} \times {2 \over 3}} \right)$$ <br><br>= ${1 \over {18}} + {1 \over {18}}$ <br><br>= ${1 \over 9}$

About this question

Subject: Mathematics · Chapter: Probability · Topic: Classical and Axiomatic Probability

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