Do the data provide evidence that the mean speed of each design does not meet the target value of 67.4 km/h? Answer the question by carrying out the appropriate statistical tests. (a) Carry out an appropriate test to check the above claim using the data for each design. Use an appropriate significance level corresponding to the confidence level in Question 3. In particular, state the null and alternative hypotheses in terms of the population parameters, obtain the value of the test statistic, specify the distribution of the test statistic under the null hypothesis, and obtain the p-value of the test. What do you conclude? (Note that you will have to calculate the value of the test statistic and the corresponding p-value by entering appropriate formulas into Excel worksheet. Lab 4 Instructions may be useful in this part.) (b) What are the assumptions about the distribution of speed required to make the tests in part (a) valid? Do the assumptions hold? Explain briefly. It is not required to verify the assumptions with Excel. Are these the same assumptions as the intervals in Question 3? Why