Rate of change in a cone
I am a beginner and could use help solving this problem:
water flows out of a cone shaped reservoir at 50m^3/min. the reservoir water level 6m h when full and the radius is 45m. when the water level is at 5m, (a) how fast is the water level falling and (b) at that moment how fast is the radius changing.
So I think dv/dt = 50 and I need to find dh/dt and dr/dt, right?
I was trying to use dv/dt=1/3*pi*r^2*dh/dt + 1/3*2r*dr/dt*h.
I know the answers but I am having trouble getting there
Well I have r1/h1=r/h so r1/5=45/6 and r1=37.5.
I get lost subbing it in the equation above. am I using the right equation?