Hello,

Here are general rules for the standard normal distribution (and it will look very logical if you look at a z-table : http://www.science.mcmaster.ca/psych...e/z-table2.jpg)

define p(.) as the black area. it's defined for positive values.

Ifa>0

P(Z>a)=0.5-p(a)

P(Z<a)=1-P(Z>a)=0.5+p(a)

Ifa<0

P(Z<a)=P(Z>-a)=0.5-p(-a)

P(Z>a)=P(Z<-a)=0.5+p(-a)

P(a<Z<b)=P(Z<b)-P(Z<a)

and that's all ^^