3. Sketch a function such that for x0 and f"(x)>0 and for x>3 f'(x)0 Then f'(3) = ? 4. Water is pumped into a tank at a rate of r(t) = 30(1 - e- 1of ) gallons per minute, where / is the number of minutes since the pump was turned on. If the tank contained 800 gallons of water when the pump was turned On, then how much water is in the tank at time t=30 min? Show work