The probability that the oldest child is a girl is given by the quotient between two numbers:
- The number of combinations where a girl is the oldest child i.e. the number of elements in the sample space that start with a G.
- The total number of elements in the sample space.
The first number is 4 since we have 4 elements starting with G: GBB, GBG, GGB, GGG. The second number is 8. Therefore the probability that we are looking for is given by:
[tex]P=\frac{4}{8}=\frac{1}{2}[/tex]AnswerThen the answer is 1/2.