Owing to several major ocean oil spills by tank vessels, Congress passed the 1990 Oil Pollution Act, which requires all tankers to be designed with thicker hulls. Further improvements in the structural design of a tank vessel have been proposed since then, each with the objective of reducing the likelihood of an oil spill and decreasing the amount of outflow in the event of a hull puncture. To aid in this development, Marine Technology (Jan. 1995) reported on the spillage amount (in thousands of metric tons) and cause of puncture for 42 major oil spills from tankers and carriers. [Cause of puncture is classified as collision (C), fire/explosion (FE), hull failure (HF), or grounding (G).] The data are saved in the accompanying file.
a. Use a graphical method to describe the cause of oil spillage for the 42 tankers. Does the graph suggest that any one cause is more likely to occur than any other? How is this information of value to the design engineers?
b. Find and interpret descriptive statistics for the 42 spillage amounts. Use this information to form an interval that can be used to predict the spillage amount of the next major oil spill.