CFA Level I Sampling and Estimation - Confidence Intervals

CFA Level I
#1

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

#2

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