(b) the water level drops at a rate of 0.1 cm per hour. at what rate is the radius of the water decreasing when the depth is 4 cm? round your answer to four decimal places.

ifferentiate your correct answer to a) with respect to time: 2rdrdt=46dhdtâ’2hdhdt You are told that dhdt=â’0.1 Figure out what the radius r is when the depth h=4 Then you will have all of the values (except one) to plug into the differentiation above. Solve for drdt. It should be a negative number, because the radius is decreasing.