Introductory Biostatistics

.3997 (area between 0 and 1.28), so that

Prðzb 1 : 28 Þ¼ 0 : 5 
Prð 0 aza 1 : 28 Þ

¼ 0 : 5 
 0 : 3997

F 0 : 10

In terms of the question asked, there is approximately a 0.1 probability of
obtaining azvalue of 1.28 or larger.

3.2.3 Normal Distribution as a Probability Model

The reason we have been discussing the standard normal distribution so
extensively with many examples is that probabilities for all normal distributions
are computed using the standard normal distribution. That is, when we have a
normal distribution with a given meanmand a given standard deviations(or

Figure 3.9 Graphical display for Example 3.5.

Figure 3.10 Graphical display for Example 3.6.

128 PROBABILITY AND PROBABILITY MODELS