Standard Normal Distribution 標準常態分配
The standard normal distribution has a bell-shaped density with mean
and standard deviation
The standard normal distribution is denoted by N(0,1) or Z.
The two events [Z<-1.9] and [Z>2.1] are incompatible, so we add their
As indicated in follow, P[Z>2.1] is the area to the right of 2.1, which is
The normal table gives
P[Z<-1.9]=.0287 directly. Adding these two quantities, we get