1. The demand and cost functions for a product are p(x) = 130 - 0.01x and C(x) = 30x + 1100, where x is the number of units produced weekly. If the manufacturer decides to increase production by 70 units per week, find the rate at which profit is changing with respect to time when the weekly production is 3600 units.
2. A rocket travels vertically at a speed of 500 km/hr. The rocket is tracked through a telescope by an observer located 18 km from the launching pad. Find the rate at which the angle between the telescope and the ground is increasing 3 min after lift-off.
3. A boat is pulled in to a dock by a rope with one end attached to the front of the boat and the other end passing through a ring attached to the dock at a point 6 ft higher than the front of the boat. The rope is being pulled through the ring at the rate of 0.4 ft/sec. How fast is the boat approaching the dock when 10 ft of rope is out?