EXAMPLE 12 Finding the -value

For each of the following hypothesis tests, calculate and graph the -value.

To review how to calculate these probabilities, see Table 8 in Chapter 6 on page 355.

Solution

  1. We have a right-tailed test, so that the -value equals the area in the right tail:

    The table gives the probability for . Thus,

    (Figure 6a)

  2. We have a left-tailed test, so that the -value equals the area in the left tail:

    (Figure 6b)

    509

  3. Here, we have a two-tailed test, so that the -value equals the sum of the areas in the two tails:

    image
    Figure 9.6: FIGURE 6a -Value for a right-tailed test.
    image
    Figure 9.7: FIGURE 6b -Value for a left-tailed test.
    image
    Figure 9.8: FIGURE 6c -Value for a two-tailed test.

NOW YOU CAN DO

Exercises 7–20.