48. Exercise 34 presented the following data on endotoxin concentration in settled dust both for a sample of urban homes and for a sample of farm homes:

U: 6.0 5.0 11.0 33.0 4.0 5.0 80.0 18.0 35.0 17.0 23.0 F: 4.0 14.0 11.0 9.0 9.0 8.0 4.0 20.0 5.0 8.9 21.0 9.2 3.0 2.0 0.3

a. Determine the value of the sample standard deviation for each sample, interpret these values, and then contrast variability in the two samples. [Hint:
xi
237.0 for the urban sample and
128.4 for the farm sample, and
x2 i
10,079 for the urban sample and 1617.94 for the farm sample.]

b. Compute the fourth spread for each sample and compare.

Do the fourth spreads convey the same message about variability that the standard deviations do? Explain.

c. The authors of the cited article also provided endotoxin concentrations in dust bag dust:

U: 34.0 49.0 13.0 33.0 24.0 24.0 35.0 104.0 34.0 40.0 38.0 1.0 F: 2.0 64.0 6.0 17.0 35.0 11.0 17.0 13.0 5.0 27.0 23.0 28.0 10.0 13.0 0.2 Construct a comparative boxplot (as did the cited paper) and compare and contrast the four samples.