1. The problem statement, all variables and given/known data "A man pours water into a conical glass (with radius 9cm and height 6cm) at a rate of 8cm^3. At what rate is the height of the water changing per second when the height of the glass is 2/3rd's full of water? NOTE: The answer is supposedly 2/9(pi) cm/sec. I am supposed to show that this is right. 2. Relevant equations V= 1/3*(pi)*r^2*h h = (3V)/(2*(pi)^2) 3. The attempt at a solution I tried to differentiate the h equation that I found above. Then, after differentiating, I subbed in the radius (6) and the Volume (48). Note that I found the radius to be 6, and volume to be 48 when the height is 2/3rds (and thus, 4). However, after I diff and then plug, I always come up with a negative answer. Thanks for any help.