Chapter 4, Problem 4.2P

Interpretation Introduction

Interpretation:

The fraction of observations in ideal Gaussian distribution lies within given $\text{μ}$ values has to be identified.

Concept Introduction:

Area under the graph for z >0:

The standard normal distribution is symmetric about its mean, z = 0. Also, the total area under the standard normal probability distribution equals 1. Taken together, these two factors imply that the areas on either side of the mean z =0, equal 0.5. Thus, the area to the leftt of z = 0, that is, z < 0 is 0.5. Thus, the area under the graph for z <0 is 0.5.