Assume that the depth of the water in a pond, y, in meters, is given by the function of time, t, in hours after midnight, by the function y= 11+ 8.5 cos(0.45t) What is the rate of change in meters per hour (positive is rising, negative is falling) of the depth of the water at the following times? At 6:00 am, the rate is meters per hour. At 9:00 am, the rate is 4 meters per hour. At noon, the rate is At 6:00 pm, the rate is meters per hour. meters per hour.