In a sample of 15 F/A-18E Super Hornet fighter engines inspected, 3 had cracked turbine blades. Use MINITAB to obtain a 95 percent confidence interval for the population proportion with cracked...

In a sample of 15 F/A-18E Super Hornet fighter engines inspected, 3 had cracked turbine blades. Use MINITAB to obtain a 95 percent confidence interval for the population proportion with cracked turbine blades, both assuming normality and without assuming normality. Is normality justified? (See Aviation Week & Space Technology 149, no. 24 [December 14, 1998], p. 18.)