Hi all! I'm having trouble with some Calc homework, and I'm hoping you can help me. Here goes:

V= 4600 * [1-(t/38)]^2 , 0 [< or equal to] t [< or equal to] 38

Find the rate at which the water is draining from the tank after:

a). 4 minutes

b). 9 minutes

c). 17 minutes

I think you just take a derivative and the plug in for t, but I'm having a hard time with finding the derivative.