Bacteria in Hospital Carpeting Researchers wanted to discover whether the median amount

Chapter 15, Problem 11

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Bacteria in Hospital Carpeting Researchers wanted to discover whether the median amount of bacteria in carpeted rooms was greater than the median amount of bacteria in uncarpeted rooms. To determine the amount of bacteria in a room, researchers pumped the air from the room over a Petri dish at the rate of 1 cubic foot per minute for 8 carpeted rooms and 8 uncarpeted rooms. Colonies of bacteria were allowed to form in the 16 Petri dishes. The results are presented in the following table: Carpeted Rooms (bacteria/cubic foot) Uncarpeted Rooms (bacteria/cubic foot) 11.8 10.8 12.1 12.0 8.2 10.1 8.3 11.1 7.1 14.6 3.8 10.1 13.0 14.0 7.2 13.7 Source: William G. Walter and Angie Stober. Microbial Air Sampling in a Carpeted Hospital. Journal of Environmental Health 30:405, 1968. Is the median amount of bacteria in carpeted rooms greater than the median amount of bacteria in uncarpeted rooms? Use the a = 0.05 level of significance.