Final answer:
The null hypothesis (H0) for testing AAA's claim would be that the proportion of fatal accidents caused by driver error is 54% (H0: p = 0.54), while the alternative hypothesis (Ha) would denote a decrease in this proportion (Ha: p < 0.54). The test would be conducted at a 10% significance level.
Step-by-step explanation:
Defining Null and Alternative Hypotheses
To determine if the percentage of fatal car/truck accidents caused by driver error has decreased from the previously reported 54%, we need to establish the appropriate null and alternative hypotheses. The null hypothesis (H0) is the claim stating no change from the standard or previously known value, that is, we assume the proportion of driver error accidents remains the same (p = 0.54). The alternative hypothesis (Ha) represents the researcher's belief in the change, which in this case is that the proportion has decreased (p < 0.54).
Therefore, the two hypotheses for this test would be stated as:
When performing the test at a 10% level of significance (alpha = 0.10), if the p-value calculated from the test statistic is less than alpha, the null hypothesis would be rejected, supporting the researcher's claim that the percentage has decreased.