The data for the 42 recent spills are saved in the accompanying file.
a. Construct a 90% confidence interval for the difference between the mean spillage amount of accidents caused by collision and the mean spillage amount of accidents caused by fire/explosion. Interpret the result.
b. Conduct a test of hypothesis to compare the mean spillage amount of accidents caused by grounding to the corresponding mean of accidents caused by hull failure. Use α = .05.
c. Refer to parts a and b. State any assumptions required for the inferences derived from the analyses to be valid. Are these assumptions reasonably satisfied?
d. Conduct a test of hypothesis to compare the variation in spillage amounts for accidents caused by collision and accidents caused by grounding. Use α = .02.
For Information: Refer to the Marine Technology (Jan. 1995) study of major oil spills from tankers and carriers. Exercise 2.159.