Discrete Math
posted by Jessica .
Find z so that 5% of the area under the standard normal curve lies to the right of z.
the answer according to the book is 1.645, anyone got any ideas on how to get this?

I assume you have either a chart for the normal distribution values, some kind of software, or you can use the internet.
Since you want 5% to lie to the right of the z score, then 95% would lie to the left of the z score.
Find .95 in the body of the table and it should be in around 1.645
My favourite is the following webpage, it replaces your old tables from your old textbooks
http://davidmlane.com/normal.html
choose button : Value from an area
In Area: enter .95
click on "below" and "recalculate"
you should see 1.645
btw, enter .05 in area, then click on "above", then "recalculate"
how about that? 
ok that makes sense, thanks.