Q31 / 60 · JEE Advanced 2014 (Paper 2) · Mathematics

Paragraph: Box $1$ contains three cards bearing numbers $1,2,3$; box $2$ contains five cards bearing numbers $1,2,3,4,5$; and box $3$ contains seven cards bearing numbers $1,2,3,4,5,6,7$. A card is drawn from each of the boxes. Let $x_{i}$ be the number on the card drawn from the $i^{t h}$ box, $i=1,2,3$.
Question: The probability that $x_{1}+x_{2}+x_{3}$ is odd, is

  • A
    29105
  • Correct answer
    B
    53105
  • C
    57105
  • D
    12

Solution

Case I: One odd, 2 even
Total number of ways =2×2×3+1×3×3+1×2×4=29
Case II: All 3 odd
Number of ways =2×3×4=24
Favourable ways = 53
Required probability =533×5×7=53105

Hence, the correct answer is option: 'B'.

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