Assume that each born child is equally likely to be a boy or a girl. If two 

families have two children each, then the conditional probability that

all children are girls given that at least two are girls is:

  • Option 1)

    \frac{1}{11}

  • Option 2)

    \frac{1}{10}

  • Option 3)

    \frac{1}{12}

  • Option 4)

    \frac{1}{17}

 

Answers (1)

There are 4 children 

\thereforetotal number of ways in whcih atleast 2 girls are there

GGGG\rightarrow _{4}^{4}C\textrm{}

GGGB\rightarrow _{3}^{4}C\textrm{}

GGBB\rightarrow _{2}^{4}C\textrm{}

_{4}^{4}C\textrm{}+ _{3}^{4}C\textrm{}+ _{2}^{4}C\textrm{}=11

Required probabilty = \frac{all\: \: 4\: \: are\: \: girls}{11}

P=\frac{1}{11}

Option (1) is correct.


Option 1)

\frac{1}{11}

Option 2)

\frac{1}{10}

Option 3)

\frac{1}{12}

Option 4)

\frac{1}{17}

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