Chapter 11, Problem 41CE

An investigation of the effectiveness of an antibacterial soap in reducing operating room contamination resulted in the accompanying table. The new soap was tested in a sample of eight operating rooms in the greater Seattle area during the last year. The following table reports the contamination levels before and after the use of the soap for each operating room.

At the .05 significance level, can we conclude the contamination measurements are lower after use of the new soap?