(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.
Answer:
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.
