Answer:
[tex]\displaystyle \frac{7}{8}[/tex].
Step-by-step explanation:
If two events are complements, then the sum of their probabilities should be [tex]1[/tex].
This question suggests that the following two events are complements:
As a result:
[tex]\begin{aligned}& P(\text{at least one child is female}) \\ &= 1 - P(\text{all three children are male})\end{aligned}[/tex].
According to the question,
[tex]\displaystyle P(\text{all three children are male}) = \frac{1}{8}[/tex].
Therefore,
[tex]\begin{aligned}& P(\text{at least one child is female}) \\ &= 1 - P(\text{all three children are male}) \\ &= 1 -\frac{1}{8} \\ &= \frac{7}{8}\end{aligned}[/tex].