your above-ground pool has sprung a leak, and you do not have a way to fix it. At 12 noon, the water in the pool is 5 feet deep.(in other woords, the water level is 5 feet above the ground.) You are not sure how quickly the pool level is falling, so you check again after 40 minutes and see that the height of the water level is now 4 feet. You nottice that there is a relationship between the time has passed to the height of the water level in the pool.