Micropropagation (tissue culture) is a cloning technique where small pieces of plant tissue (explants) are grown in vitro on nutrient agar. Design a laboratory investigation to determine how varying the concentration of the plant growth regulator indole-3-butyric acid (IBA), an auxin, in the agar medium affects the rooting success (number of roots developed) of cauliflower (Brassica oleracea) explants. Your answer should include experimental details and be written in full sentences.