A study of the effectiveness of an antibacterial soap in reducing operating room contamination was conducted in 8 operating rooms. The contamination levels before and after the use of the soap is reported below. At the .05 significance level, can we conclude that the mean contamination levels were reduced after the use of the soap? The data are reported below:

Before 6.6 6.5 9.0 10.3 11.2 8.1 6.3 11.6 After 6.8 4.7 7.4 8.5 8.1 6.1 3.4 7.2

a. Enter the letter corresponding to the correct null and alternate hypotheses. A. H₀: _d 0 H₁: _d < 0

B. H₀: _d 0 H₁: _d > 0

C. H₀: _d = 0 H₁: _d 0

b. What is the level of significance?

c. Which test statistic will be used, z or t?

d. Enter the letter corresponding to the correct decision rule? A. Reject H₀ if t > 1.895

B. Reject H₀ if z < 1.645

C. Reject H₀ if t > 2.365

e. Calculate the value of the test statistic. Round your answer to three decimal places.

f. Enter the letter corresponding to the correct decision regarding the null hypothesis. A. Reject H₀

B. Do not reject H₀

g. Enter the letter corresponding to the correct answer to the question asked in the problem. A. Yes, the mean contamination levels were reduced after the use of the soap.

B. No, the mean contamination levels were not reduced after the use of the soap.