Question

find the critical value $z_{alpha/2}$ that corresponds to the confidence level 99%.
$z_{alpha/2}=square$
(round to two decimal places as needed.)

Explanation:

Step1: Calculate significance level $\alpha$

$\alpha=1 - 0.99 = 0.01$

Step2: Calculate $\frac{\alpha}{2}$

$\frac{\alpha}{2}=\frac{0.01}{2}=0.005$

Step3: Find $z_{\alpha/2}$ from standard - normal table

Looking up the $z$ - value corresponding to an area of $1 - 0.005=0.995$ in the standard - normal distribution table, we get $z_{\alpha/2}=2.58$

Answer:

$2.58$