A hand sanitizer was advertised to be more effective at killing bacteria than any
antibacterial soap. Students were split evenly into 4 groups to test this claim.
Groups 1-3 washed their hands using the assigned hand sanitizer or soap and
warm water for two minutes, and then dried their hands with a paper towel.
Group 4 rubbed their hands vigorously for 2 minutes in warm water, without any
soap or sanitizer, and then dried their hands with a paper towel. After washing,
each student's hands were swabbed and the swab was applied to a culture plate
and incubated. Finally, the bacterialſ cultures were counted. What group is the
control group?
Nour answer

The control group during an experiment is a group that does not receive the treatment administered to other groups and as such used as a standard for measuring the effects of the treatment on other groups. Whatever differences that exist between the control group and the various treatment groups is attributed to be as a result of the treatment administered to the groups.

In this case, group 4 only used warm water for washing their hands instead of the hand sanitizer/soap used by the other groups. Whatever differences found out in the bacterial count in their respective culture swabs can be attributed to the effects of the hand sanitizer/soap.