The U.S. Army commissioned a study to assess how deeply a

Chapter 7, Problem 18E

(choose chapter or problem)

Problem 18E

The U.S. Army commissioned a study to assess how deeply a bullet penetrates ceramic body armor ("Testing Body Armor Materials for Use by the U.S. Army-Phase III," 2012). In the standard test, a cylindrical clay model is layered under the armor vest. A projectile is then fired, causing an indentation i n the clay. The deepest impression in the clay is measured as an indication of survivability of someone wearing the armor. Here is data from one testing organization under particular experimental conditions; measurements (in mm) were made using a manually controlled digital caliper:

22.4 23.6 24.0 24.9 25.5 25.6

25.8 26.1 26.4 26.7 27.4 27.6

28.3 29.0 29.1 29.6 29.7 29.8

29.9 30.0 30.4 30.5 30.7 30.7

31.0 31.0 31.4 31.6 31.7 31.9.

31.9 32.0 32.1 32.4 32.5 32.5

32.6 32.9 33.1 33.3 33.5 33.5

33.5 33.5 33.6 33.6 33.8 33.9

34.1 34.2 34.6 34.6 35.0 35.2

35.2 35.4 35.4 35.4 35.5 35.7

35.8 36.0 36.0 36.0 36.1 36.1

36.2 36.4 36.6 37.0 37.4 37.5

37.5 38.0 38.7 38.8 39.8 41.0

42.0 42.1 44.6 48.3 55.0

a. Construct a boxplot of the data and comment on interesting features.

b. Construct a normal probability plot. Is it plausible that impression depth is normally distributed? Is a normal distribution assumption needed in order to calculate a confidence interval or bound for the true average depth pausing the foregoing data? Explain.

c. Use the accompanying Minitab output as a basis for calculating and interpreting an upper confidence boundforiswithaconfidencelevelof99%.