A truck accident dumped a toxic chemical into a river that feeds into the pond in Giuseppe's town. He knows that the concenctration of the chemical C can be modelled by

where t is the time since the accident in hours. Giuseppe uses the model to prepare a crisis plan for the pond.

Once the concentration falls below 8mg/L, it is safe for divers to enter the pond to save the remaining fish.

When the concentration decreases to 4mg/L, the park bordering the pond may reopen.

Finally, the river also feeds into the water plant that provides the town's tap water, and the tap water will only be safe for drinking and cooking once the concentration falls to 2mg/L.