User`s guide

Statistical Calculations
135
Example 3
The variable Z is a standard normal random variable. Find z so that the probability that Z is
less than z and greater than -z is equal to 0.95.
Figure 19
The given area is 0.95. The area not included is 1-0.95/2 = 0.025. Since the normal
distribution is symmetrical, half of the desired area is in the lower tail, .05/2=.025. The
desired area corresponds to a lower tail probability of .025.
Table 12-25 Example converting from lower tail (the inner area)
Keys Display Description
7:GV]oF
-1.959964 Returns desired value of z.