Travel and Transportation Highway engineers have long argued that roads designed with high skid…
Travel and Transportation Highway engineers have long argued that roads designed with high skid resistance help to prevent accidents, especially in wet conditions. A random sample of two-lane highways was selected from across the United States, and the skid resistance was measured (in skid numbers) using a Skid Resistance Tester (SRT). The accident rate (per 10,000 vehicles) was computed for 25-mile sections of each highway during wet conditions.
a. Identify the independent variable and the dependent variable.
b. Construct a scatter plot for these data, and describe the relationship between the two variables.
c. Find the estimated regression line.
d. Suppose the skid resistance is 0.50. Conduct a hypothesis test to determine whether there is any evidence that the true mean accident rate is less than 0.60. Use a significance level of 0.05.