A pebble is thrown into a pond and the radius of the circula

A pebble is thrown into a pond and the radius of the circular ripple expanding at the rate of 2 inches per second when the rate is 6 inches. Find the rate at which the area of the circle is expanding

area, A= pi*r^2 change in area = dA = 2*pi*r*dr given r = 6in and dr = 2 in/s put all values, dA = 75.4 m^2/s