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 implemented since then, each with the objective of reducing the likelihood of an oil spill and decreasing the amount of outflow in the event of hull puncture. To aid in this development, J. C. Daidola reported on the spillage amount and cause of puncture for 50 recent major oil spills from tankers and carriers.

The data are reproduced in the table on p. 35 (Marine Technology, Jan. 1995).

a. Use a graphical method to describe the cause of oil spillage for the 50 tankers.

b. Does the graph, part

a, suggest that any one cause is more likely to occur than any other? How is this information of value to the design engineers?