A horticulturalist investigated the effect of different concentrations of indole-3-butyric acid (IBA), a synthetic auxin, on the root development of lavender stem cuttings.
The concentrations of IBA used for the five treatment groups were:
Group A is a control treatment containing 0 ppm0\text{ ppm}0 ppm of IBA. Explain the purpose of including Group A in this investigation.
Calculate how many times more concentrated the IBA is in Group E than in Group B. Show your working.