An oil well off the Gulf Coast is leaking, with the leak spreading oil over the water's surface as a circle. At any time t, in minutes, after the beginning of the leak, the radius of the circular oil slick on the surface is r(t)=2t feet. Let A(r)=3.14r^2 represent the area of a circle of radius r.

(a) Find (A o r)(t)

(b) Interpret (A o r)(t)

(c) What is the area of the oil slick after 5 minutes?

The little o is the o symbol in calculus, I just don't have it on my keyboard :)