ITEMS INFO 8. Practice similar A rock is thrown into a still pond and causes a circular ripple. If the radius of the ripple is increasing at a rate of 3 feet per second, how fast is the circumference changing when the radius is 18 feet? Change in circumference =9. Practice similar Suppose that two boats leave a dock at different times. One heads due north, the other due east. Find the rate at which the distance between the boats is changing when the first boat is 39 miles from the dock traveling at a speed of 33 miles per hour and the second boat is 76 miles from the dock traveling at a speed of 24 miles per hour. Answer:10. Practice similar The radius of a spherical balloon is increasing at a rate of 2 centimeters per minute. How fast is the volume changing when the radius is 8 centimeters? Note: The volume of a sphere is given by V = (4/3) mr3. Rate of change of volume =11. Practice similar (1 point) A ladder 10 ft long rests against a vertical wall. If the bottom of the ladder slides away from the wall at a speed of 2 ft/s, how fast is the angle between the top of the ladder and the wall changing when the angle is w/4 rad? rad/ s12. Practice similar Suppose that x = x(t) and y = y(t) are both functions of t. If y' try- 3x = -11, and dy/dt = -4 when x = 3 and y = -2, what is dx / dt? dx / dt = Submit answer13. Practice similar