Find the critical value z Subscript alpha divided by 2 that corresponds to the given confidence level. 80%

With the confidence level we can find the significance level:

And the value for . Then we can use the normal standard distribution and we can find a quantile who accumulates 0.1 of the area on each tail and we got:

Step-by-step explanation:

For this problem we have the confidence level given

With the confidence level we can find the significance level:

And the value for . Then we can use the normal standard distribution and we can find a quantile who accumulates 0.1 of the area on each tail and we got: