Question

In a classic experiment carried out by the biologist Hopkins in the 20th century, 20 young rats were divided into two groups. One group was fed on a diet of pure carbohydrate, lipid and protein; the other was fed the same diet, but with some added milk. The rats were weighed every day. After 18 days the diets of the groups were swapped over.

why did Hopkins use 2 sets of rats?

suggest some important control variables that Hopkins kept constant during his investigation.

Answer 1

If he uses 20rats he can average the results so the results are more realistic BC not all rats have the same metabolism so if he used just to they could end weighting the same because one has a better metabolism but with twenty its the average of all the rats who are all different.