State the conclusion based on the results of the test. According to the report, the standard deviation of monthly cell phone bills was $\$ 48.51$ three years ago. A researcher suspects that the standard deviation of monthly cell phone bills is less today. The null hypothesis is not rejected. Choose the correct answer below. A. There is sufficient evidence to conclude that the standard deviation of monthly cell phone bills is different from its level three years ago of $\$ 48.51$. B. There is not sufficient evidence to conclude that the standard deviation of monthly cell phone bills is less than its level three years ago of $\$ 48.51$. C. There is sufficient evidence to conclude that the standard deviation of monthly cell phone bills is less than its level three years ago of $\$ 48.51$.
Solution
Step 1 ：The question is asking us to interpret the results of a statistical test. The null hypothesis, which is the assumption that there is no significant difference between specified populations, is not rejected. This means that there is not enough evidence to support the researcher's suspicion that the standard deviation of monthly cell phone bills is less today.
Step 2 ：Therefore, the correct answer should be B. There is not sufficient evidence to conclude that the standard deviation of monthly cell phone bills is less than its level three years ago of $48.51.
Step 3 ：Final Answer: \(\boxed{\text{B. There is not sufficient evidence to conclude that the standard deviation of monthly cell phone bills is less than its level three years ago of \$48.51}}\).
