CFA Level I Sampling and Estimation - Confidence Intervals

[HJC]

https://i.imgur.com/ASlRqWe.png
I keep checking the Z tables and I dont know how you get 2.58?
I know the 99% confidence interval means we have 0.5 on both sides of the normal distribution tales, but where do you get 2.58 from?
Thanks

 

[Abh]

For certain std. confidence intervals there are critical values of z:
eg.
90% - 1.65
95% - 1.96
98% - 2.33
99% - 2.58
These are typically taken from the Z-Table