Find each of the following. Enter your answers rounded to at least two decimal places. Part 1 of 5 $z_{\alpha / 2}$ for the $90 \%$ confidence interval \[ z_{\alpha / 2}=\square \]

Step 1 ：We are asked to find the z-score for a 90% confidence interval. This is denoted as \(z_{\alpha / 2}\).

Step 2 ：We use the scipy.stats library in Python to calculate the z-score. The function norm.ppf(0.95) is used because the z-score for a 90% confidence interval is the percentile point at 0.95 (or 95%).

Step 3 ：The Python code returns a z-score of approximately 1.6448536269514722.

Step 4 ：We round this to at least two decimal places to get the final answer.

Step 5 ：The z-score for a 90% confidence interval is approximately \(\boxed{1.645}\).