Question: A mosquito sucks 20 drops of blood every time it feeds on someone. If there are 5000 drops per liter and you have to lose 3 liters of blood to die, how many mosquitoes would have to feed on you to kill you? Think carefully first, then make a decision:
First find the total number of liters a mosquito sucks in one feeding: 20 drops / 5000 drops / liter = .004 L / feeding. Then divide the lethal amount of blood by the amount of blood one mosquito can drain: 3 L / .004 L / feeding = 750 feedings. So the answer is 750.