Hand washing versus hand rubbing. Refer to the British Medical Journal (Aug. 17, 2002) study comparing the effectiveness of hand washing with soap and hand rubbing with alcohol, presented in Exercise 2.107

(p. 106). 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 hand washing 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 1x2 is less than 30. Give your opinion on whether this sample of workers used hand rubbing with alcohol or hand washing with soap.