A rock is thrown into a still pond. The circular ripples move outward from the point of impact of the rock so that the radius of the circle formed by a ripple increases at the rate of 5 feet per minute. Find the rate at which the area is changing at the instant the radius is 9 feet. When the radius is 9 feet, the area is changing at approximately square feet per minute. (Round to the nearest thousandth as needed.)