Page 175 - Probability Demystified

164 CHAPTER 9 The Normal Distribution

This table gives the approximate cumulative areas for z values between
3 and þ3. The next three examples will show how to find the area (and
corresponding probability in decimal form).

EXAMPLE: Find the area under the standard normal distribution curve to
the left of z ¼ 1.3.

SOLUTION:
The area is shown in Figure 9-11.

Fig. 9-11.

In order to find the area under the standard normal distribution curve to
the left of any given z value, just look it up directly in Table 9-1. The area is
0.903 or 90.3%.
EXAMPLE: Find the area under the standard normal distribution curve
between z ¼ 1.6 and z ¼ 0.8.

SOLUTION:

The area is shown in Figure 9-12.

Fig. 9-12.