9. A Balloon is rising vertically over a point A on the ground at the rate of 15 ft/ sec. A point B on the ground is level with and 30ft from A. When the balloon is 40 ft. at the rate is its distance from B changing?

10. There is a constant inflow of the liquid into a conical vessel 15 feet deep and 7.5 feet in the diameter at the lop. Water is rising at the rate of 2 feet per minute when the water is 4 feet deep. What is the rate if the inflow in cu. f per minute?