Question

Find the critical value z Subscript alpha divided by 2 that corresponds to the confidence level 90​%.

Answer 1

For this problem we know that the confidence level is 90% so then we can find the significance level with:

`\alpha=1-0.90 = 0.1`

Then the value of
`\alpha/2=0.05` and we can find a quantile who accumulate 0.05 of the area on each tail of the normal standard distribution and for this case the critical values are:

`z_(\alpha/2)= 1.64`

Explanation:

For this problem we know that the confidence level is 90% so then we can find the significance level with:

`\alpha=1-0.90 = 0.1`

Then the value of
`\alpha/2=0.05` and we can find a quantile who accumulate 0.05 of the area on each tail of the normal standard distribution and for this case the critical values are:

`z_(\alpha/2)= 1.64`