7. An object is thrown upward from the ground with an initial velocity of 136 feet per second. a. At what time will the object reach its maximum height? b. What will the maximum height be? 8. The radius of a circle is increasing at a rate of 8 cm/second. Find the rate at which the area is changing when the radius is 25 cm. 9. A circle is expanding at a rate of 75 square inches per second. Find the rate at which the radius is increasing when the radius is 12 inches. 10. As a spherical balloon is being inflated with helium, the rate of flow into the balloon is 200 cubic cm per second. How fast is the radius increasing when the radius is 25 cm