You are babysitting your two younger siblings of ages 3 and 6. You watch YouTube and ignore them. A half hour the later the 6 year old comes in and tells you, long story short, your little brother has ingested an unknown quantity of medication X a half hour ago. As a young mathematician and medic, you check your brother's blood for harmful substances and see there is only one possible thing that could harm him: he currently has a concentration of 0.02 g/ml of substance X in his blood stream. 

You know that the concentration decreases proportionally to the amount of concentration of the substance at a given time. Furthermore, you know that the proportion by which it decreases is some- where in between 1 and 2. You deduce that there will only be cause for concern if the initial concentration of substance X in his blood stream surpassed 0.05 g/ml. Do you need to call an ambulance? Or can you get back to YouTube without being worried?