Answer
$\mu$ is between 0.491 and 0.947.
Work Step by Step
Given mean:0.719.
Given $\sigma$:0.366.
$\alpha=1-0.9=0.1.$ $\sigma$ is known, hence we use the z-distribution using the table. $z_{\alpha/2}=z_{0.05}=1.645.$ Margin of error:$z_{\alpha/2}\cdot\frac{\sigma}{\sqrt {n}}=1.645\cdot\frac{0.366}{\sqrt{7}}=0.228.$ Hence the confidence interval:$\mu$ is between 0.719-0.228=0.491 and 0.719+0.228=0.947.
