Related Rates and Volume and Change in height

[Qube]

Homework Statement

http://i6.minus.com/jErr8PMddiofz.png

Homework Equations

V of cone = pi/3 (r^2)h

The Attempt at a Solution

I'm assuming this is correct and that dh/dt = 0.2 ft/min

I basically substituted a value of h in for the radius so I wouldn't be doing multi-var calculus and differentiated from there using the chain rule as needed.

http://i.minus.com/jUeLLF0Kxg3hp.jpg

 

[haruspex]

I didn't check the arithmetic in the final step, but it looks fine down to there.

 

[Qube]

Alright great :-)! Thanks ::)