Answer:
[tex] Conf= 0.80[/tex]
With the confidence level we can find the significance level:
[tex]\alpha =1-0.8=0.2[/tex]
And the value for [tex]\alpha/2=0.1[/tex]. 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:
[tex] z_{\alpha/2}= \pm 1.28[/tex]
Step-by-step explanation:
For this problem we have the confidence level given
[tex] Conf= 0.80[/tex]
With the confidence level we can find the significance level:
[tex]\alpha =1-0.8=0.2[/tex]
And the value for [tex]\alpha/2=0.1[/tex]. 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:
[tex] z_{\alpha/2}= \pm 1.28[/tex]
