The Use of Carpeting in Hospitals, While Having Aesthetic Value

question 17

Multiple Choice

The use of carpeting in hospitals, while having aesthetic value, raises an obvious question: Are carpeted floors sanitary? An experiment comparing airborne bacteria levels in carpeted rooms with that in uncarpeted rooms was performed in an effort to answer this question. Specifically, for each of eight carpeted rooms and eight uncarpeted rooms in a hospital, the number of bacteria per cubic foot of air was measured. The data are given below. Assume that room sizes are equal, and that the 16 rooms in this experiment were assigned randomly to the carpet and no-carpet groups. If W, the Wilcoxon rank sum test statistic, is the sum of the ranks assigned to the carpeted group, and if the two populations have the same continuous distribution, then the standard deviation of W is:

• A)2.32.
• B)8.51.
• C)9.52.
• D)90.67.

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Definitions:

Syphilis

A sexually transmitted infection caused by the bacterium Treponema pallidum, presenting in various stages from sores to serious systemic symptoms.

Lyme Disease

An infectious disease caused by the Borrelia bacteria, transmitted to humans through the bite of infected black-legged ticks.

Spirilla

A genus of spiral-shaped bacteria, some of which are known to cause diseases in humans.

Viruses

Infectious agents that replicate only inside the living cells of an organism, which can cause a variety of diseases in humans, animals, and plants.