Q95 / 200 · WBJEE 2014 · Mathematics

Ram is visiting a friend. Ram knows that his friend has 2 children and 1 of them is a boy. Assuming that a child is equally likely to be a boy or a girl, then the probability that the other child is a girl, is

  • A
    $1 / 2$.
  • B
    $1 / 3$
  • Correct answer
    C
    $2 / 3$
  • D
    $7 / 10$

Solution

Total sample space $=\left\{B_{1} B_{2}, B_{1} G_{1}, G_{1} B_{2}\right\}$ Favourable ways $=\left\{B_{1} G_{1}, G_{1} B_{2}\right\}$ $\therefore$ Required probability $=\frac{2}{3}$

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

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