Question 1182737
if the confidence level is 87%, that means the alpha = 1 minus .87 = .13.
alpha / 2 is therefore equal to .065.
the critical z-score will therefore be plus or minus 1.514101887.


this can be seen in the following displays using the z-score calculator that can be found at <a href = "https://davidmlane.com/hyperstat/z_table.html" target = "_blank">https://davidmlane.com/hyperstat/z_table.html</a>


<img src = "http://theo.x10hosting.com/2021/070605.jpg" .


<img src = "http://theo.x10hosting.com/2021/070606.jpg" >


<img src = "http://theo.x10hosting.com/2021/070607.jpg" >


<img src = "http://theo.x10hosting.com/2021/070608.jpg" ?