Answer
Yes, it is.
Work Step by Step
We know that the proportions are as follows:
Proportion of girls, probability
0, 1/8
1/3, 3/8
2/3, 3/8
1, 1/8
We know the sample proportion is 1/2. Thus, using the table above, we find that the population proportion is:
$\frac{1}{3}(\frac{3}{8})+\frac{2}{3}(\frac{3}{8})+\frac{1}{1}(\frac{1}{8})=.5$
We see that the sample proportion is an unbiased predictor of the population proportion, for the sample and population proportions are the same.
