Answer
$0.25\pm 0.085.$
Work Step by Step
$\hat{p}$ is the sample average of the boundaries, hence:$\hat{p}=\frac{0.165+0.335}{2}=0.25.$
E is half of the confidence interval, hence:$E=\frac{0.335-0.165}{2}=0.085$, hence the confidence interval:$0.25\pm 0.085.$
