In July 2013 a train carrying 72 tank cars filled with oil exploded and rolled off the tracks in Lac-MÃ©gantic, Quebec. This was one of the worst train accidents in Canadian history, and the disaster prompted many to discuss improved regulations for the transportation of hazardous materials. The Association of American Railroads reported that the safety record for moving hazardous materials is outstanding, and that 74% of railroad crude-oil spills involve less than five gallons.73 Over the next year, a random sample of 129 railroad crude-oil spills was obtained, and 85 involved spills of less than five gallons.
a. Is there any evidence to suggest that the proportion of crude-oil spills that involve less than five gallons has decreased? Use a 5 0.05.
b. Explain the practical implications of the hypothesis test results in part (a).
c. Find the p value associated with this hypothesis test.