Question

A scientist wishes to determine how effective a vaccine is in protecting rats against a contagious disease. What experimental procedure should the scientist use to determine the vaccine's effectiveness?

Answer 1

Shouldn't she vaccinate half the rats and then expose all of them to the disease?

Answer 2

give vaccinations to 50 of the 100 rats and then expose all 100 to the disease

Answer 3

Give vaccinations to 50 of the 100 rats and then expose all 100 to the disease

Answer 4

D) vaccinate 50 of the 100 rats and then expose only 50 vaccinated rats to the disease.

Answer 5

Vaccinate 50 of the rats then expose only the 50 vaccinated rats to the disease