How do I solve for speed

8. CalC3102s 10 pts possible A rock is thrown into a still pond and causes a circular ripple. If the radius of the ripple is SUBMIT ANSWER increasing at a rate of 4 ft/sec, at what speed 1. speed = 177 sq. ft/sec is the area of the ripple increasing when its radius is 2 feet? 2. speed = 187 sq. ft/sec 3. speed = 17 sq. ft/sec 4. speed = 197 sq. ft/sec 5. speed = 19 sq. ft/sec 6. speed = 16 sq. ft/sec 7. speed = 167 sq. ft/sec 8. speed = 20 sq. ft/sec