The following is 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...

The following is 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:
Σx_i
= 237.0 for the urban sample and = 128.4 for
the farm sample, and Σx_i
²
= 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