Given data
*The given mean is u = 2.3 pounds
*The total number of macaw parts is n = 38
*The given standard deviation is Q = 0.20 Pounds
Z-score for 90% confidence interval is Z = 1.645
The formula for the confidence interval is given as
![s=u\pm\frac{zQ}{\sqrt[]{n}}](https://img.qammunity.org/2023/formulas/mathematics/college/vuapnrfd066uaunkv4vxocptdsptlfgwjv.png)
Substitute the values in the above expression as
![\begin{gathered} s=2.3\pm\frac{1.645*0.20}{\sqrt[]{38}} \\ =2.3\pm0.05337 \\ =2.24,2.35\text{ pounds} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/vnjz6yfqjbnl8k1uytwekj4w2yvdv9lfel.png)