Chapter 5.3, Problem 5.35ACA

Handwashing vs. handrubbing. The British Medical Journal (August 17, 2002) published the results of a study to compare the effectiveness of handwashing with soap and hand rubbing with alcohol. Health care workers who used hand rubbing had a mean bacterial count of 35 per hand with a standard deviation of 59. Health care workers who used handwashing had a mean bacterial count of 69 per hand with a standard deviation of 106. In a random sample of 50 health care workers, all using the same method of cleaning their hands, the mean bacterial count per hand, $\bar{x}$, is less than 30. Give your opinion on whether this sample of workers used hand rubbing with alcohol or handwashing with soap.