EXAMPLE 8 Finding and the critical region

For the hypotheses,

where represents the population mean systolic blood pressure, let the level of significance .

  1. Find the critical value .
  2. Graph the distribution of , showing the critical region.

Solution

We have a left-tailed test and level of significance , so Table 4 tells us that the critical value is . The graph showing the critical region is provided in Figure 2. We would reject for values of that are .

image
Figure 9.2: FIGURE 2 Critical region for a left-tailed test lies in the left (lower) tail.

NOW YOU CAN DO

Exercises 23–26.