A scientist randomly divided a group of 100 lab rats into two groups of 50. One group was fed regular rat chow while the other was fed the same amount of rat chow with added DDT. Both groups were housed in the same room with the same environmental conditions. At the end of the experiment, rats were weighed and the mean difference calculated.
-Refer to the accompanying narrative. Which variable(s) were manipulated by the scientist?
A)DDT only
B)temperature only
C)weight differences only
D)both DDT and weight differences
E)both temperature and weight differences

Question

Quizplus · Accepted Answer

The variable manipulated by the scientist was the addition of DDT to the rat chow for one of the groups, making DDT the independent variable in this experiment.

A Scientist Randomly Divided a Group of 100 Lab Rats