Question 1108219
wow, you said a mouthful.


i think what you're looking for is the interval between the two end points, where the area in between is .8.


.8 in between means .2 outside which is divided by 2 to get .10 on each end.


.10 would be your alpha / 2.


to find the area with .8 in between, you would find the z-score for an area of.9 to the left of it and the z-score for an area of .1 to the left of it.


the area between the z-scores would be the area in between.


the z-score with an area to the left of it equal to .9 would be z = 1.281551567.


the z-score with an area to the left of it it equal to .1 would be z = -1.281551567.


the area in between is .8.


a picture of what what would look like is shown below.


<img src = "http://theo.x10hosting.com/2018/020101.jpg" alt="$$$" >


i'm assuming you are able to find the area to the left of a z-score and to find the z-score with a specified area to the left of it.


if you need help with that, let me know and i'll give you some more detailed instructions.


the calculator with the picture can also be used, but it will spoil you.


bet you learn how to do it the hard way first, so you have that up your sleeve in case you need it.


here's the link to the online calculator i used.


<a href = "http://davidmlane.com/hyperstat/z_table.html" target = "_blank">http://davidmlane.com/hyperstat/z_table.html</a>


here's a link to a table if you want to use that.


<a href = "http://www.stat.ufl.edu/~athienit/Tables/Ztable.pdf" target = "_blank">http://www.stat.ufl.edu/~athienit/Tables/Ztable.pdf</a>


let me know if this is what you wanted and, if not, what you might have been looking for that is not what i provided.